LIBRARY OF CONGRESS. 

8h.elf.'.E.Z5 



UNITED STATES OF AMERICA. 



AN 



INDEI OF PHYSIOLOGY, 



L. ASHLEY FAUGHT, D.D.S., 



Member of the Odontographic Society of Pennsylvania; 

Late Lecturer on Physiology in the Philadelphia 

Dental College; Member of the Academy of 

Natural Sciences of Philadelphia, etc. 



i^ 



H 




PRESS OF 

WM. H. HOSKINS, 913 ARCH STREET, 

1881. 



r 



^1 

a5 



Copyright. 
L. ASHLEY FAUGHT. 



TO 

ALBERT H. SMITH, M. D., 

IN APPRECIATION OF HIS HIGH PROFESSIONAL CHARACTER, 

AND IN ACKNOWLEDGMENT OF HIS MANY ACTS 

OF PERSONAL KINDNESS, 

THIS BOOK 
IS AFFECTIONATELY DEDICATED. 



PREFACE. 



The Index of Physiology makes no pretension 
as a contribution to original investigation ; but has 
been compiled with the view of giving to the advanced 
student, a ready and complete reference book of 
physiological facts; and to the novice, a clear founda- 
tion for more mature study. 



1 1 25 Arch St., Philadelphia. 
October j, 1881. 



CONTENTS 



General Physiology .... 


5— 


7 


Classification of Nature . 


8— 


12 


Proximate Principles . . . 


13— 


17 


Tissues 


18— 


19 


Alimentation . . . . . 


20 — 


21 


Digestion 


21 — 


39 


Absorption ..... 


40— 


42 


The Blood 


43— 


45 


Circulation of the Blood . 


46- 


51 


Respiration .... 


52— 


55 


Secretion ..... 


56- 


57 


Excretion 


58- 


66 


Nutrition and Animal Heat 


67- 


69 


Movements 


70— 


75 


The Nervous System . . . 


. 76- 


98 


The Special Senses 


99— 


113 


Generation . . . . 


. 114— 


120 


Sleep and Death 


121 — 


122 


Table of Specific Gravities 


122 — 





AN INDEX OF PHYSIOLOGY, 



DEFINITION OF PHYSIOLOGY.— Physiolog}- is 
the science of life. Life is the sum of the functions. 
FUNCTIONS. — A function is that which an organ 
does. There are three kinds of functions ; nutritive, 
animal or of relation, and reproductive. The nutritive 
NUTRITIVE FUNCTIONS.— functions are diges- 
tion, absorption, circulation, respiration, nutrition, ca- 
lorification and secretion. The animal functions are 
ANIMAL FUNCTIONS— sensation, mental and 
moral manifestations, muscular motion, and expression 
REPRODUCTIVE FUNCTION.— or language. 
Generation is the reproductive function. 

VITAL PHENO:^IENA._Vital phenomena are 
simple physical phenomena, acting under peculiar 
conditions and circumstances. 

THE CELL. — The smallest particle of matter in 
any organism is a cell, it being the elementary unit. 



6 AN INDEX OF PHYSTOLOG K 

THE GLOBULE.— The term cell is applied to vege- 
table formations, globule, to animal ones. Three 
ORGANISMS. — kinds of matter compose all organ 
isms : — bioplasm, formed material and pabulum. Bio- 
BIOPLASM. — plasm is germinal matter, or matter that 
FORMED MATERIAL._is living ; formed material 
PABULUM. — is matter that was living ; and pabulum 
is matter about to become living. A cell is composed 
COMPOSITION OF A CELL._of a wall filled with 
protoplasm, containing nuclei and nucleoh. It is spher- 
FORM. — ical in form, homogeneous and compact, with 
water as its dominant element, — constituting by weight 
nearly four-fifths of each. A peculiar property of 
cells, is their tenacity of composition in spite of sur- 
BiRTH. — rounding elements. Each cell is born of 
another, in a fluid known as blastema. The division of a 
SEGMENTATION.—parent cell into two, four, or a 
multiple, is called segmentation ; and when after seg- 
mentation, the cells still remain within the wall of the 
ENDOGENESIS. — parent cell, the term endogenesis 
is applied. There are four kinds of cells : — epithelial, 
KINDS OF CELLS. — nerve, blood and embryonic. 
THE CONDITIONS OF LIFE. —For the mainte- 
nance of life, three chemical conditions are required ; 



GENERAL PHYSIOLOGY. 7 

a supply of air, water and combustible material. The 
AVERAGE WEIGHT OF MAN.— average weight of 
man is one hundred and forty pounds. The heat 
HEAT OF THE BODY— of the body arises from 
combustion. 

THE KINGDOMS OF NATURE.— The king- 
doms of nature are the organic and the inorganic, — 
the former including vegetables and animals, — the 
latter, minerals and gases. They difter in origin, 
DIFFERENCE BETWEEN THE ORGANIC AND 
THE INORGANIC.—shape, size, chemical com- 
position and growth ; these being for the most part 
definite in the organic, but indefinite in the inorganic \ 
while growth occurs in the inorganic by accretion, but 
in the organic, from within. The marked distinction 
DIFFERENCE BETWEEN VEGETABLES AND 
ANIMALS. — between vegetables and animals is that 
the latter possess the power of sensation and voluntary 
motion, which the former do not. To test for origin, 
burn the substance, and the presence or absence of an 
unmistakable animal odor will determine the kind. 



CLASSIFICATION OF NATURE. 



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CLASSIFICA 7 ION OF NA TURK. .9 

ARCHETYPES— Animals are classified into arch- 
etypes, from some particular plan of structure, observ- 
able in them. The archetype vertebrata, (latin, ver- 
VERTEBRATA. — tere, to turn,) includes animals 
possessing a vertebral column. An example is man. 
ARTICULATA. — Animals formed of segments are 
called articulata, (latin, articulus^ a joint.) An ex- 
MOLLUSCA. — ample is the lobster. The pecuhar 
characteristic of the mollusca is softness, (latin, mollis , 
soft.) x\n example is the oyster. Animals radiating 
RiVDIATA. — from a centre are called radiata, (latin, 
radius J a rod.) An example, the star-fish. The 
PROTOZOA. — archetype protozoa, (greek, profos, 
first; and zooii, an animal,) includes microscopical 
animals, found especially in water. 

CLASSES. — The classes are based upon some 
special action or function peculiar to each. The 
PISCES. — class pisces, includes the fishes, and is 
peculiar by living in water. Creeping animals, ser- 
REPTILIA. — pents, lizards, the tortoise, etc., are in- 
cluded under the head of reptilia, (latin, repto, 1 
AMPHIBL\. — creep.) The class amphibia, (greek,- 
amphi, both ; and bios, life, ) includes animals like the 
frog, living in two elements. The class aves, includes 



I O CLA SSIFICA TION OF NA TURE. 

AVES. — animals which fly, and possess horny bills. 
Example, birds. The class mammalia (latin, ma?nma, 
MAMMALIA. — a breast,) includes animals possessing 
mammary glands to suckle their young. Animals 
VI VIP AR A. — bringing forth their young in a mature 
state, are termed vivipara, (latin, vivuSy alive; and 
parioy I bring forth.) The sub-class ovovivipara, 
OVOVIVIPARA. — (latin, ovum, an tgg ; viviis, alive ; 
and pario, I bring forth,) includes animals which bring 
forth their young in an immature state. 

ORDERS. — The division into orders, is based upon 
well marked peculiarities of structure. Animals pos- 
PLACENTALIA. — sessing a placenta, are called pla- 
IMPLACENTALIA. — centalia; those which do not, 
implacentalia. The sub-class unguiculata, (latin, 7in' 
UNGUICULATA. — guis, a nail,) includes animals 
having nails or claws. The sub-class ungulata, (latin, 
UNGULATA. — tmgtiia, a hoof,) includes animals 
with hoofs. The order bimana, (latin, bis, twice; 
BIMANA. — ^.\\&?nanus, a hand,) includes animals hav- 
ing two hands, and the oppo;:.ible thumb. Man only. 
The order quadrumana, (latin, quatuor, four; and 
QUADRUMANA. — ;//<^;2^^, ahand,) includes animals 
having four hands. Monkeys, etc. The order 



CLASSIFICATION OF NATURE. \l 

CHEIROPTERA.—cheiroptera, (greek, cheir, a 
hand ; and pteron, awing,) possess winged hands, hke 
INSECTIVORA. — the bat. The order insectivora, (lat- 
in, insectus^ an insect ; and z;^r^, I devour, ; inckides an- 
imals feeding upon insects, as the mole and hedge- 
CARNIVORA. — hog. The order carnivora, (latin, 
carfiis^ flesh; and voro, I devour,) includes animals 
which live upon flesh, as the lion. The order 
CETACEA. — cetacea, (latin, ceius^ a whale.) includes 
RODENTIA.— all animals like the whale. The order 
rodentia, (latin, rodo, I gnaw,) includes animals which 
EDENTATA. — gnaw, as the rat. Animals without 
teeth are called edentata, (latin, e, without ; and dens, 
a tooth.) An example is the armadillo. The hard 
PACHYDERMATA.— skinned animals, as the horse, 
elephant, etc., are called pachydermata, (greek, 
pacchus, thick; and derma, a skin.) The order 
RUMINANTIA. — ruminantia, (latin, riiviino, I chew 
the cud,) includes animals having a compound 
stomach ; and no front teeth in the upper jaw, if an 
exception is made of the camel. The females of the 
MARSUPIATA. — ^order marsupiata, (latin, marsup- 
iiim, a pouch,) have a pouch for the reception of their 
young on birth. Examples, the kangaroo and opos- 



1 2 CLASSIFICA flON OF NA TURE, 

sum. The order monotremata (greek, monos, one ; 
MONOTREMATA.— and /r^;;/^, a hole,) includes 
animals having a common outlet for the generative and 
excremental products, as the ornithorynchus. 

FAMILIES. — The distinction of families, is founded 
upon some modification of form or structure. The 
GENERA. — division into genera, is based upon some 
difference in the number of teeth and claws. The 
SPECIES. — division into species, is based upon some 
difference in color, proportion and size. 



PROXIMATE PRINCIPLES. 



DEFINITION OF A PROXIMATE PRINCIPLE. 
— A proximate principle is any substance, simple or 
compound, which- exists under its own form, in an 
animal solid or fluid : and which can be extracted by 
means that will not destroy its properties. 

PROTINACEOUS COMPOUNDS.— The protina- 
ceous compounds are: — Protiene, N.C.H.O. : albu- 
men.. N.C.H.O.P.S. : fibrine. NC.H.O.P.S. : and 
caseine, N.C.H.O.S. 

HYDRO-CARBONACEOUS PROXIMATE 
PRINCIPLES. — The h}'dro-carbonaceous proximate 
principles are : — Starch, glycogen, sugar, glucose, lac- 
tose, saccharose, fats, stearine, palmatine. oleine and 
cholesterine. 

ALBUMINOUS MATTERS.— The albuminous 

13 



14 PROXIMATE PRINCIPLES. 

matters are : — Fibrine, albumen; albuminose, caseine, 
ptyaline, pepsine, pancreatine, mucosine, myosine, 
collagen, chondrine, gelatine, elastacine, keratine., 
cartilagine. 

COLORING MATTERS— The coloring matters 
are: — Haemaglobine, melanine, biliverdine, uro- 
chrome, luteine, chlorophylle and bilirubine. 

CRYSTALLIZABLE NITROGENOUS MAT- 
TERS. — -The crystallizable nitrogenous matters are : — 
Lecathine, cerebrine, leucine, sodium glycholate, so- 
dium taurocholate, creatine, creatinine, urea, sodium 
urate and sodium hippurate. 

STARCH. — Starch is found in various forms in the 
body. Glycogen is a sugar forming substance; — an 
GLYCOGEN. — animal starch capable of being changed 
SUGAR. — into glucose. Sugar exists in the body in 
GLUCOSE. — various forms. Glucose is grape sugar, 
DEXTROSE. — and is found in the liver. Dextrose is 
a form of grape sugar found in the liver, and in veins 
LACTOSE. — leaving that organ. Lactose is found 
FATS. — in milk. Fats are soluble in ether, but in- 
OLEINE. — soluble in water. Oleine is a fluid fat. 
Margarine is a supposed mixture of stearin e and palma- 
STEARINE. — tine. It is a solid fat. Stearine is a 



PR OX IMA TE PRINCIPLES. \ 5 

PALMATINE. — solid fat. Palmatine is a solid crys- 
CHOLESTERINE.— tallizable fat. Cholesterine is 
found in the bile and brain. 

FIBRINE. — Fibrine is found in the blood, chyle, 
and lymph. Albumen is found in the white substance 
ALBUMEN. — of eggs, in the brain, in nerves, and in 
the blood. It is soluble in water. Vegetable albumen 
exists in turnips, asparagus, etc. Albuminose is found 
ALBUMINOSE. — in the body, being formed during 
the process of digestion from albuminoid articles. 
CASEIN E. — Caseine is found in milk, and does not 
coagulate by heat. Ptyaline or salavin, is an album- 
PTYALINE. — inoid substance found in the saliva. It 
PEPSINE. — converts starch into dextrine. Pepsine 
is the active principle of the gastric juice. Pancreatine 
PANCREATINE. — is found in the pancreatic juice, 
MUCOSINE. — and seems to emulsify fats. Mucosine 
MYOSINE. — is found in mucus. Myosine is found 
coagulated after death, in the contra- tile substance of 
COLLAGEN. — striped muscular tissue. Collagen is 
found in bones, ligaments, etc. Chondrine is a form of 
CHONDRINE. — gelatine, obtained from bones by 
GELATINE. — boiling under pressure. Gelatine is 
found in tendoiis and ligaments. Elastacine is found in 



1 6 PROXIMATE PRINCIPLES. 

ELASTACINE. — all elastic .issues. Keratine is found 
KERATINE. — in hair, nails and epidermis. Cartila- 
CARTILAGINE. — gine is found in cartilage. Haem- 
HAEMAGLOBINE. — aglobine is the coloring matter 
MELANINE.— of the blood. Melanine is a black 
BILIVERDINE. — coloring matter. Biliverdine is the 
green coloring matter of the bile. Urochrome is the 
UROCHROME. — amber coloring matter of the 
LUTEINE. — urine. Luteine is the yellow coloring 
found in the yolk of eggs, and in the corpus luteum. 
CHLOROPHYLLE.— Chlorophylleis the green color- 
ing matter in plants and leaves. Bilirubine is the 
BILIRUBINE. — orange coloring matter in the bile. 
LECITHINE. — Lecithine is found in the brain, 
CEREBRINE. — spinal cord and nerves. Cerebrine 
LEUCINE. — is found in the brain. Leucine is found 
in the spleen, pancreas and pancreatic uice. Sodium 
SODIUM GLYCHOLATE.— glycholate is found in 
SODIUM TAUROCHOLATE.— the bile. Sodium 
taurocholate is a p:culiar ingredient of the bile. Crea- 
CREATINE. — tine is found in the juice of muscle and 
CREATININE.— in the blood. Creatinine is found 
UREA . — in the juice of muscle and in the blood. Urea 
is found in urine. It crystallizes in four-sided prisms, is 



PROXIMATE Principles. 17 

soluble in water, and neutral in reaction to test paper. 
SODIUM URATE. — Sodium urate is found in urine. 
SODIUM HIPPURATE.— Sodium hippurate is found 
in urine, and is so-called because it was first obtained 
from that of the horse. 




TISSUES. 

PHYSICAL PROPERTIES OF TISSUES._The 

physical properties of tissues are : — Elasticity, extensi- 
bility, porosity, endosmose and exosmose. By elasticity 
ELASTICITY. — is meant the capability of being drawn 
out, with the pow^r of resuming the original shape. By 
EXTENSIBILITY. — extensibility is meant the posses- 
sion of the power of being drawn out or lengthened. 
POROSITY. — By porosity is meant the possession of 
pores, or resembling a sponge. By endosmose is meant 
ENDOSMOSE. — the power a liquid has to pass from 
without a membrane, to the inside. By exosmose is 
EXOSMOSE. — meant the power a liquid has to pass 
from within a membrane to the outside. 

VITAL PROPERTIES OF TISSUES— The vital 
properties of tissues are : — Contractility, nervous force, 
common sensation and special sensation. Contractility 

CONTRACTILITY.— is the power which a tissue has 

i8 



TISSUES. 19 

of shortening upon itself. Nervous force is that 
NERVOUS FORCE. — property possessed by nerves, 
of being called into action by an appropriate stimulus. 

COMMON SENSATION— Common sensation is 
that recognition of impressions by nervous tissue, which 
is general to the body. Special sensation is that 
SPECIAL SENSATION.— recognition of impressions 
by nervous tissue, which is special to a part or organ, 
and possessed by no other. 

KINDS OF TISSUE.~The kinds of tissue found 
in the body are : — Connective tissue, areolar tissue, 
fibrous tissue, elastic tissue, adipose tissue, cartilagin- 
ous tissue, osseous tissue, muscular tissue, nervous tis- 
sue, membraneous tissue, and epidermic tissue. The 
MODIFICATIONS OF TISSUE.— modifications of 
tissue are :— The hair, nails, teeth, the humors and 
other portions of the eye. 



ALIMENTATION. 



APPETITE. — Appetite is the pleasant desire for 
HUNGER. — food; while hunger is the painful desire 
for food. Thirst is a general expression of the entire 
system lor drink, and is located apparently in the 
tongue and fauces. 

AQUEOUS FOOD.— Aqueous food, (H. O.) in- 
cludes water or water holding important elements in 
solution. The saccharineous articles of food (C. H. O. ) 
SACCHARINEOUS FOOD.— are :— Sugar, starch, 
OLEAGINOUS FOOD.— gums and vinegar. Olea- 
ginous food includes oils, fats and alcohol. The albu- 
ALBUMINOUS FOOD.— minous ardcles of food 
are : — iVlbumen, fibrine, caseine, and vegetable gluten. 
DIVISION OF FOOD.— Food is divided into nitro- 
genous and non-nitrogenous. Nitrogenous food is nu- 
NITROGENOUS FOOD.— tritive or histeogenetic. 
NON-NITROGENOUS FOOD.— Non-nitrogenous 
food is calorifacient or heat producing. 



DIGESTION. 



DIGESTI'ON. — Digestion is the process by which 
food is prepared for absorption ; the first stage is 
PREHENSION. — prehension and consists in taking 
food and placing it in the mouth, by organs which act 
for this purpose, namely, — the bill in birds; the hands 
in man ; the trunk in the elephant ; the lips and teeth 
ORGANS OF PREHENSION— in ruminants; and 
the claws and teeth in carnivorous animals. The mouth 
THE MOUTH. — is a cavity lined by mucous mem- 
brane, and bounded above by the hard palate ; on 
LINING. — each side by the cheek; anteriorly, by the 
lips ; on the bottom by muscular structure ; and pos- 
teriorly by the pharynx, separatecT by the velum. In 
it are situated the organs of the second stage of diges- 
ORGANS OF MASTICATION.—tion,— mastication, 
which are divided into the active and passive. 

PASSIVE ORGANS OF MASTICATION.— The 

21 



22 DIGESTION. 

passive organs are : the masticatory bones, the liga- 
ments and the teeth. The masticatory bones are the 
MASTICATORY BON ES . —superior and inferior max- 
illae, or upper and lower jaw bones ; and the palate 
bones. The superior maxillary bones afe two in num- 
SUPERIOR AND INFERIOR MAXILLARY 
BONES. — ber ; while the inferior maxillary bones, ex- 
isting as two in the foetus, become united later in life, 
and appear as one in the adult. The palate bones are 
THE PALATE BONES— two in number, and are 
situated back of the superior maxillary. Articulated 
GOMPHOSIS. — with the jaws by the alveolar process, 
THE TEETH. — constituting gomphosis, are the teeth; 
the hard organs of mastication, situated in the aliment- 
ary canal, anterior to the pylorus. They do not belong 
RELATION. — to the skeleton, but to the digestive tract, 
and each is anatomically divided into a crown, neck 
THE CROWN. — and root. The crown is that portion 
above the gums ; the root, that portion below them ; 
THE ROOT AND NECK.—and the neck, the con- 
stricted portion between the crown and the root. There 
SETS OF TEETH.— are two sets of teeth,— the tempo- 
rary and the permanent. In the former, there are 
TEMPORARY. — twenty teeth, — ten in each jaw; while in 



DIGESTION. 



23 



PERMANENT. — the latter there are thirty-two, — sixteen 
TYPICAL FORM OF A TOOTH.— in each jaw. The 
typical form of a tooth is a cone. The incisor teeth 
INCISOR TEETH. — are the four in each jaw, occupy- 
SHAPR. — ing the anterior portion of the arch. They are 
LABIAL SURFACE. — wedge-shapecl, and present a labial 
PALATINE SURFACE. — siirface. toward the lips: a pala- 
cuTTiNCx EDGE. — tine surface toward the palate : a 
cutting edge, formed by the union of the palatine 
and labial surfaces : a mesial surface, toward the 
MESIAL SURFACE. — Central line of the mouth, forming 
with the cutting edge nearly a right angle ; and 
DISTAL SURFACE. — a distal surface, looking away 
from the central line of the mouth, and rounded 
in its union with the cutting edge. These teeth are 
divided into centrals and laterals : the upper centrals 
SIZE. — being larger than the upper laterals, while the 
lower centrals are smaller than the lower laterals. 
The incisor teeth have a single root, conical in shape. 
ROOTS. — The root of the laterals is more flattened 
than that of the centrals. The cuspid teeth, are situ- 
THE CUSPIDS. — ated next to the incisors, and pre ■ 
ROOT. — sent a single crown, with a single root, which 
is the longest in the head. The bicuspid teeth are 



24 DIGESTION. 

THE BICUSPID TEETH.— four in each jaw, and 
ANTERIOR SURFACE. — present an anterior surface, as 
the one nearest the median Hne ; a posterior surface, 
POSTERIOR SURFACE. — toward the back of the mouth ; 
BUCCAL SURFACE. — a buccal surface, toward the cheek; 
LINGUAL SURFACE. — and a Ungual surface, toward 
the tongue. They have, as a rule, a single root, with 
ROOTS. — a tendency to become double, and superior 
first bicuspids often have two roots. The molar teeth 
THE MOLAR TEETH. — are six in each jaw, and 
present four or {\\^ cusps, having in the lower mouth 
usually two roots, and in the upper, three. The teeth 
are so articulated with one another, that each tooth 
ORAL TEETH. — has two antagonists. The canines 
and incisors are called the oral teeth. All the 
POSITION OF ROOTS.— roots of the teeth look 
away from the median line of the mouth. 

TOOTH GERMS.— In the development of the 
teeth, tooth germs are never found upon the surface, 
and every known tooth germ consists, at first, of two 
portions ; — the enamel germ and the dentine germ, 
ENAMEL GERM.— The former comes from the 
DENTINE GERM. — mucous membrane of the mouth; 
and the latter, from the sub -mucous tissue. The 



DIGESTION. 25 

earliest change that will result in the formation of a 
DEVELOPMENT OF THE TEETH— tooth is 
observable about the fortieth day of uterine life, and 
consists of a slight rounded depression of the mucous 
membrane of the mouth, which at a later period be- 
comes enlarged and slightly indentated in the base. 
DENTINE PULP. — Rising into this indentation, is a 
portion of the sub-mucous tissue, the future dentine 
pulp. Around the sides of the dipping down, is 
columnar epithelium, and its central space, is filled 
ENAMEL PULP.— with stellate cells. This structure 
is known as the enamel pulp, and from it is formed 
the enamel of the tooth; — the columnar epithelium 
becoming converted into the enamel prisms. The 
DENTINE. — odontoblast cells of the dentine pulp 
are converted into dentine ; while the free edges of 
this pulp extend up around the enamel organ, becom- 
TOOTH SAC. — ing known as the tooth sac, and 
ALVEOLO-DENTAL MEMBRANE.— subsequently, 
CEMENTLTM. — the alveolo-dental membrane. From 
it is formed the cementum. 

CALCIFICATION OF DENTINE.— The calcifi- 
cation of the dentine begins before that of the enamel, 
and is formed from without, inwards ; the uncalcified 



26 DIGESTION, 

DENTINAL FIBRILS— portion of the odontoblast 
cells, bemg the dentinal fibrils; and the portion of the 
DENTINAL PULP.— dentine pulp, uncalcified, being 
the dentinal pulp. The outer layer of odontol)last 
MEMBRANA EBORIS.— cells on the dentinal pulp 
constitutes the membrana eboris. The enamel is 
CALCIFICATION OF ENAMEL. —formed from 
within, outwards. 

ERUPTION OF THE TEETH.— The teeth erupt 
in the following order, the lower generally preceding 
the upper by a few weeks : 

DECIDUOUS SET.— 
2 Central Incisors erupt between 5th and 8th mos. 
2 Lateral -^ '-' '' 7th '^ loth '' 

2 Canines '' '^ 12th *• i6th 

4 Molars '-' '' 14th '' 36th -• 

PERMANENT SET.— 

2 Central Incisors erupt between 6th and 8th years. 

2 Lateral '' -^ '' 

2 Canines *^ ^^ 

2 I St Bicuspids <* ^^ 

2 2nd '' '' '' 

2 I St Molars '' '' 

2 2nd '' '' '' 

2 3rd ^' ** '^ 



7th 


'^ 9th '' 


nth 


'' 1 2th " 


9t.h 


'^ loth '' 


loth 


'' nth '' 


5th 


'' 6th '' 


1 2 th 


'' 14th '' 


17th 


'^ 25th ^^ 



DIGESTION. 



27 



ABSORPTION OF THE ROOTS OF THE 
TEMPORARY TEETH.— The roots of the tempo- 
rary teeth are absorbed by a retrograde metamor- 
phosis. 

ENAMEL. — The enamel is composed of hex- 
agonal prisms, and is the hardest structure in the 
Ijody, forming the crowns of the teeth. The dentine 
DENTINE. — is softer than the enamel, and torms the 
body of the tooth, being a hard, elastic substance, of 
a yellowish tinge ; its mass consisting of an organic 
DENTINAL TUBULL— matrix, in which are tubes, 
known as dentinal tubuli. The cementum covers 
CEMENTUM.— the roots of the teeth, and is closely 
alHed, in nature, to bone. It overlaps the enamel 
NASMYTH'S MEMBRANE.— at the neck, and is 
supposed to cover, in a thin layer, the entire crown, 
forming Nasmyth's membrane. In the centre of every 
PULP CAVITY.— tooth is the pulp cavity ; and in it 
PULP. — is the formative organ of the tooth, — the pulp. 

ACTIVE ORGANS OF MASTICATION— The 
active organs of mastication are : — the temporal, mas- 
seter, and pterygoid muscles. The temporal muscle is 
TEMPORAL MUSCLE.— fan shaped, and arises 
ORIGIN. — from the temporal bone, to be inserted 



28 DIGESTION, 

INSERTION. — into the coronoid process of the lower 
jaw. The masseter muscle lies directly under the 
MASSETER MUSCLE.— skin, on the side and back 
ORIGIN. — of the face; arising from the superior max- 
INSERTION. — ilia, malar bone, and zygomatic process. 
ACTION. — It is inserted into the external side of the 
ramus, and into the angle of the lower jaw, acting to 
elevate the mandible. The external pterygoid muscle 
EXTERNAL PTERYGOID MUSCLE.—arises from 
ORIGIN. — the external plate of the pterygoid process 
INSERTION. — of the sphenoid bone ; and is inserted 
into the inner side of the neck of the lower jaw. It 
ACTION. — acts to elevate and protrude the lower jaw, 
giving also lateral motion. The internal pterygoid 
INTERNAL PTERYGOID MUSCLE.— muscle arises 
ORIGIN. — from the inner surface of the pterygoid plate ; 
INSERTION. — and is inserted into the inner face of the 
angle of the lower jaw. Its action is to elevate the 
ACTION. — lower jaw, and to give lateral motion. 

THE TONGUE.— In the mouth is the tongue, a 
muscular organ, composed of two symmetrical halves, 
separated by a median fibrous septum. It is used for 
sucking, especially in the infant, where it is of the 
greatest importance. Its muscles are divided into the 



DIGESTION. 29 

MUSCLES. — extrinsic and the intrinsic. The extrinsic 
EXTRINSIC MUSCLES. — muscles are : — the hyo-glossus, 
genio-hyo-glossiis, stylo-glossus, and palato-glossus. The 
INTRINSIC MUSCLES. — intrinsic muscles are the muscles 
proper of the tongue, viz. : — The superior longitudinal, 
inferior longitudinal or lingualis, and the transverse. 

REGULATION OF MASTICATION.— The pro 
cess of mastication, through which the food is com- 
minuted, is regulated by the sensibility of the teeth to 
impressions of hard or soft substances. 

INSALIVATION.— The third stage of digestion is 
called insalivation, and consists in the incorporation 
of saliva with the food. The salivary glands are race- 
SALIVARY GLANDS.—mose, and are divided into 
three pairs ; — the submaxillary, sublingual, and parotid. 
PAROTID GLANDS.— The parotid glands are the 
SITUATION. — largest, and are situated below and in 
DUCTS. — front of the ears. They are emptied by the 
ducts of Steno. Their secretion is thin, watery, 
PAROTID SALIVA. — limpid, colorless, inodorous, 
SUBMAXILLARY GLANDS— and tasteless. The 
submaxillary glands are the second in size, and are sit- 
siTUATiON. — uated in the sub maxillary triangles of 
DUCTS. — the neck. They are emptied by the ducts of 



30 



DIGESTION. 



Wharton, which are about two inches in length, and 
open by the side of the frasnum. The submaxillary 
SUBIVLVXILLARY SALIVA.— secretion is colorless, 
limpid, inodorous, viscid, and ghitinous. The sub- 
lingual glands are situated beneath the tongue, on 
SUBLINGUAL GLANDS.— each side of the fr^num, 
DUCTS. — and are emptied by from eight to twenty 
SUBLINGUAL SALIA^A.— ducts. Their secretion 
is more viscid than the submaxillary saliva. The 
SALIVA. — amount of saliva ordinarily secreted, -is 
SPECIFIC GRAVITY. — about three pounds daily, with a 
REACTION. — specific gravity of 1004. In reaction, it is 
FUNCTION. — constantly alkaline. The function of 
saliva is to soften hard articles of food, to coat the 
bolus with a glairy covering, facilitating its being 
swallowed ; and possibly to entangle air, which in the 
stomach would hasten the penetration of the gastric 
juice. 

DEGLUTITION.— The fourth stage of digestion 
is deglutition, and consists in swallowing the food ; 
the passage of which through the isthmus of the fauces 
is voluntary ; while its passage through the pharynx 
and oesophagus is involuntary. The tongue is the 
THE TONGUE.— chief a^ent in the introduction of 



DIGESTION. 31 

THE PHARYNX. — the food into the pharynx,— an 
LENGTH. — irregular, funnel-shaped cavity, about four 
and a half inches in length, separated from the mouth 
OPENINGS INTO THE PHARYNX. —by the velum 
pendulum palati. The openings into the pharynx above 
are; — the posterior nares, and the orifices of the eusta- 
chian tubes ; while below are the larynx, and oesophagus. 
The posterior nares are protected during deglutition by 
the soft palate ; and the larynx, by the epiglottis. 

THE MUSCLES OF THE PHARYNX.— The 
muscles of the pharynx are, — the superior, middle, 
and inferior constrictors, and the stylo-pharyngeus. 
SUPERIOR CONSTRICTOR MUSCLE.—The su- 
ORiGiN — perior constrictor muscle arises from the in- 
ternal pterygoid plate of the sphenoid bone, and is 
INSERTION. — inserted into the median raphe. The 
STYLO-PHARYNGEUS MUSCLE.—stylo-pharyn- 
ORiGiN. — -geus muscle arises from the styloid process of 
INSERTION. — the temporal bone ; its fibres mingle with 
the constrictors and palato-pharyngeus, and are inserted 
MIDDLE CONSTRICTOR MUSCLE.— into the thy - 
ORIGIN. — roid cartilage. The middle constrictor arises 
from the hyoid bone and stylo-hyoid ligament, and is 
INSERTION. — inserted into the median raphe. The 



32 DIGESTION, 

INFERIOR CONSTRICl^OR MUSCLE —inferior 
ORIGIN. — constrictor arises from the thyroid and cricoid 
INSERTION. — cartilages, and is inserted into the median 
raphe. 

THE MUSCLES OF THE SOFT PALATE._The 
muscles of the soft palate are : — the levator palati, 
tensor palati, palato-glossus, palato pharyngeus, and 
LEVATOR PALATI.— azygos uvulce. The levator 
palati arises from the petrous portion of the temporal 
bone, and passes to be inserted into the soft palate. 
TENSOR PALATI.— The tensor palati arises from the 
scaphoid fossa of the sphenoid bone, winds around the 
hamular process, and is inserted into the soft palate. 
PALATO-GLOSSUS. — The palato-glossus arises from 
the side of the palate, and is inserted into the side and 
PALATO-PHARYNGEUS.— dorsum of the tongue. 
The palato-pharyngeus arises from the soft palate, and 
is inserted into the thyroid cartilage. The azygos 
AZYGOS UVUL.E. — uvulae forms the fleshy portion 
of the uvula. 

THE CESOPHAGUS. — The oesophagus is a mus- 
cular tube extending from the pharynx to the stomach. 
LENGTH. — It is about nine inches in length, and has a 
COATS. — muscular, an areolar, and a mucous coat. 



DIGESTION. 



33 



STOMACH. — The stomach is the most dilated por- 
tion of the alimentary canal, and is from thirteen to 
LENGTH. — fifteen inches in length, with a diameter in 
DIAMETER. — its widest part of five inches. Its capacity 
COATS. — is five pints. Its coats are three in number : 
— the peritoneal, muscular, and mucous. The peri- 
PERiTONEAL COAT. — toneal coat is a reflection of the 
membrane lining the general abdominal cavity, and its 
function is to present a smooth surface, allowing the 
free movements of the organs over each other and over 
MUSCULAR COAT. — the abdominal walls. The muscu- 
lar coat is formed of involuntary fibres in two layers ; 
— an external, longitudinal, and an internal, circular 
one, with a few oblique fibres. The mucous lining is 
MUCOUS COAT. — a continuation of the membrane in the 
oesophagus though different in appearance, being soft, 
velvety, and of a reddish gray color. It is covered by 
polygonal pits, with racemose glands opening into 
them; namely — the gastric and the mucous glands. 
The former, or peptic glands, are found throughout the 
PEPTIC GLANDS.— entire surface ; while the latter 
MUCOUS GLANDS. — exist principally near the py- 
loric extremity. 

GASTRIC JUICE. — The gastric juice is secreted 



34 DIGESTION. 

only in obedience to the stimulus of food ; and is a 
clear fluid of a faint, yellowish or amber tint, possess- 
ing little or no viscidity, with a specific gravity of 
SPECIFIC GRAVITY. — 1005. About fourtceii pounds are 
AMOUNT. — secreted in twenty- four hours. Pepsin or 
PEPSIN. — gasterase is its organic principle, and also in 
LACTIC ACID. — it is lactic acid. The gastric juice 
only prepares meats for their digestion in the intestine, 
ACTION OF GASTRIC JUICE.—but acts readily 
upon albumen, filbrine, caseine, and gelatine ; making 
ALBUMINOSE. — a colorless fluid with a feeble odor, 
called albuminose, as the result of digestion. The 
DURATION OF STOMACH DIGESTION. —aver- 
age time that food remains in the stomach after an 
ordinary meal is from two to four hours. Regurgita- 
REGURGITATION.—tion is the passage of food 
from the stomach to the mouth. Eructation is the 
ERUCTATION. — escape of gases from the stomach 
through the oesophagus and mouth. Ruminant ani- 
STOMACH OF RUMINANTS.— mals have four 
cavities in their stomach ; — the paunch, the honey- 
comb, the many-plies, and the caulet. 

SMALL INTESTINE.— The small intestine, so-call- 
ed on account of its size, extends from the pyloric extrem- 



DIGESTION. 35 

ity of the stomach, to the ileo-caecal valve ; being 
MESENTERY. — held to the spinal column by a double 
fold of serous membrane, called the mesentery. It 
LENGTH. — is in length from fifteen to eighteen feet, 
DIAMETER. — witli a diameter of one and a quarter 
DIVISIONS. — inches, and is divided into, the duodenum, 
DUODENUM.— the jejunum, and the ileum. The 
duodenum is so named from the fact that it is twelve fin- 
COATS. — gers broad, or from eight to ten inches. It has 
three coats ;— a peritoneal, a muscular of involuntary 
JEJUNUM. — fibres, and a mucous coat. The jeju- 
num, or second division, includes the upper two-fifths 
of the small intestine, deriving its name from the fact 
ILEUM. — that it is found empty after death. The 
lower three-fifths of the small intestine is named the 
ileum. The Uning mucous membrane is highly vascu- 
MUCOUS MEMBRANE OF SMALL INTESTINE. 
— lar, has a soft, velvety appearance, and presents, — 
the valvulse coniventes, the glands of Brunner, the 
follicles of Leiberkuhn, the vili, and the patches of 
VALVUL.E CONIVENTES.— Peyer. The valvuL^ 
coniventes are folds of the mucous membrane of the 
small intestine, which serve to increase the mucous 
surface aud possibly to retard the food in its passage. 



36 DIGESTION, 

GLANDS OF BRUNNER.—The glands of Brunner 
are found in the duodenum, but in no other part of 
the canal ; they are racemose, and aid in the secretion 
of the enteric fluids. The follicles of Leiberkuhn, or 
FOLLICLES OF LEIBERKUHN. —intestinal tub- 
ules, are the most important glandular structures in the 
small intestine, being the chief agents in the production 
VILI. — of the intestinal juice. The vili are chiefly 
concerned in absorption, being situated throughout the 
entire small intestine, but not found beyond the ileo- 
c?ecal valve. They are simple elevations of the mu- 
cous membrane, provided with bloodvessels and 
GLANDS OF PEYER.— lacteals. The patches of 
Peyer are found in the ileum opposite the attachment 
of the mesentery ; they exist sometimes in the jejunum 
and duodenum, and are supposed to aid absorption. 
Solitary glands, resembling in nature the glands of 
Peyer, are found both in the large and small intestines. 
INTESTINAL JUICE.—The flow of intestinal 
juice takes place normally only in response to the 
stimulus of food. It is viscid, colorless or of a rose 
tint, and in reaction, invariably alkaline. It readily 
ACTION. — converts starch into sugar, but acts only as 
a valuable adjunct to other intestinal fluids, rather 



DIGESTION. 37 

than as the digestive agent of any particular article of 
food. 

PANCREAS. — The pancreas is a glandular or- 
gan situated in the upper posterior part of the abdom- 
WEiGHT. — inal cavity. It weighs from four to five 
SIZE. — ounces, and is in lengthj seven inches; in 
breadth, an inch and a half : and in thickness, three- 
quarters of an inch. It has been called the abdom- 
inal salivary gland, and is emptied by one or tsvo 
ducts, into the duodenum. Its secretion is viscid, 
PANCREATIC JUICE.— opaline, and has a distinct 
SPECIFIC GRAVITY. — alkaline reaction, with a specific 
ACTION. — gravity of 1040. This fluid exerts an im- 
portant influence on nearly all articles of food, and 
especially upon fats, which it digests by eftecting their 
minute subdivision, in the form of an emulsion. It 
also digests starch and nitrogenized principles. 

THE BILE. — The bile has no marked influence 
upon any special class of food, but undoubtedly aids 
COLOR. — the digestive process. It is of a brownish 
SPECIFIC GRAVITY. — hue, and has a specific gra\'ity of 
REACTION. — 1018, with an alkaline reaction. It is 
supposed to influence the peristaltic action of the in- 
testine. The contractions of the muscular coat of the 



38 DIGESTION, 

MOVEMENTS OF THE INTESTINES.—small in- 
testines, propel the food along the canal, by a motion 
called peristaltic. 

LARGE INTESTINES.— The large intestine is so 
DIAMETER. — Called because it exceeds the rest of the 
intestinal tract in its diameter, which is from two and 
LENGTH. — a half to three and a half inches. It is from 
CAECUM. — four to six feet in length. Its first divi- 
RECTUM. — sion is known as the caecum, and the 
COLON. — last as the rectum : the portion between 
these two is called the colon, being divided into an 
ascending, a descending, and a transverse colon, and 
SIGMOID FLEXURE. —sigmoid flexure. At the 
VERMIFORM APPENDIX. —lower portion of the 
caecum is' a tube from one to five inches in length 
called the vermiform appendix Its use is unknown. 
ILEO-CAECAL VALVE.— The valve closing the 
opening between the ileum and the caecum, is called 
the ileo-caecal valve. The large intestine is covered 
PERITONEAL COAT.— generally by -peritoneum, 
although it is absent in some portions. The middle 
MUSCULx\R COAT. — ^"coat is muscular, the circular 
fibres of which at the anus form the sphincter ani. 
MUCOUS COAT. — The mucous co^^t differs mark- 



DIGESTION. 



39 



edly from that of the small intestine, as valvulae coni- 
ventes do not exist in any part. The large intestine 
CONTENTS OF LARGE INTESTINE. —contains 
principally residue matter^ known asfyeces; and has a 
MOVEMENTS. — motion someAvhat similar to that of the 
small intestine but far less vigorous. The expulsion of 
DEFECATION— faecal matter, which generally takes 
place once a day, is called defaecation. 



ABSORPTION. 



ABSORPTION.— The process by which materials, 
and especially digested ones, are taken into the blood 
is called absorption. The vessels performing this 
function are the bloodvessels and lymphatics. The 
LYMPHATIC SYSTEM.— lymyhatic system is di- 
vided into a superficial and a deep layer; and its 
vessels present, in many parts of their course, little 
solid structures called lymphatic glands. The lacteals 
are essentially lymphatics, and when not filled with 
the products of digestion carry colorless lymph. The 
lymphatics, except the smallest, exhibit in their con- 
struction immense numbers of valves. A marked 
peculiarity of their structure is that they vary but little 
in size. They are unevenly distributed, — few in some 
portions of the economy, and large numbers in others* 
LACTEALS. — The lymphatics of the small intestine, 

the lacteals, pass from the intestine between the folds 

40 



ABSORPTION, 41 

of mesentery, and empty by from one to five trunks 
into the receptaculum chyli. The glands through 
MESENTERIC GLANDS— which the lacteals pass 
in this location are called mesenteric glands. The re- 
RECEPTACULUM CHVLL— ceptaculum chyli is 
an enlargement of the thoracic duct, the latter being 
THORACIC DUCT.— about the size of a goose 
quill, and emptying its contents into the left sub-clav- 
ian vein. Numerous stomata or mouths exist in the 
walls of the lymphatic vessels. 

LYMPHATIC GLANDS.— There are from six to 
seven hundred lymphatic glands in the body ; and 
their function seems to be to retard the passage of the 
lymph toward the great trunks, thus aiding the arrest 
SKIN. — of morbid matters. The skin exerts an ab- 
sorbent power, especially upon water. Fats in a state 
FATS. — of emulsion are absorbed by the lacteals, and 
possibly in small quantity by the bloodvessels. Imbi- 
IMBIBITION. — ^bition is a property common to all • 
animal structures, by which they are enabled to take 
up a certain portion of a fluid. Many of the phenom- 
ena of absorption, as endosmosis and exosmosis, are 
illustrations of the power of imbibition. Chyle is 
CHYLE. — lymph plus the products of digestion, and 



42 



ABSORPTION. 



SPECIFIC GRAVITY. — has a spccific gravity of 1024 
LYMPH. — Four pounds of lymph are produced in 
twenty-four hours. It is colorless or of a yellowish 
SPECIFIC GRAVITY. — hue, has no odor, possesses a 
specific gravity of 1007, and contains corpuscular ele- 
ORiGiN. — ments known as lymph corpuscles. There 
can scarcely be any doubt but that the lymph is derived 
FUNCT'iON. — from the blood. The function of this 
material is to remove from the tissues the products of 
decay. The flow of the lymph and chyle over the 
route of the lymphatic circulation, is the result of the 
forces of endosmosis and transudation, more or less 
modified by other circumstances. 




THE BLOOD. 



THE BLOOD— The blood is the most highly or- 
ganized fluid in the body. All tissues are not supplied 
with bloodvessels, and those which are not are known 
as extra vascular tissues, being of low organization 
such as hair, cartilage, etc. In case of haemorrhage 
all the blood does not escape from the body owing to 
the diminution of the heart's force. The amount ot 
QUANTITY. — blood in the body is in the ratio of one 
to eight, — about sixteen to eighteen pounds. The 
OPACITY. — opacity of the blood depends upon the 
ODOR. — varying density of its constituents. Its odor 
TASTE. — is heavy; taste, saltish, due to chloride of 
REACTION. — sodium; the reaction, alkaline, due to 
basic carbonate and phosphate of soda ; the specific 
SPECIFIC GRAVITY. — gravity 1052 to 1057; and the 
TEMPERATURE.— temperature from 98° to 100° Fah. 

COLOR.. — The red color of the blood is due to the red 

43 



44 'T^E BLOOD. 

corpuscles, and is darker in the veins than in the arte- 
CORPUSCLES. — ries. Besides the red corpuscles 
there are in the blood the white, although the red are 
by far the most abundant and constitute about one- 
half of the mass of the blood. The white corpuscles 
or leucocytes are in the proportion of i : 700 of the 
red. The corpuscles are flattened, biconcave, circular 
RED. — discs and very elastic. The red have a spe- 
SPECiFic GRAVITY. — cific gravity of 1088 to 1105, and 
DIAMETER. — a diameter of -g^Vij ^^ ^^ inch. The 
WHITE. — leucocytes are found not only in the blood, 
but also in lymph, chyle, pus, and other fluids. Their 
SPECIFIC GRAVITY.— specificgravity is 1070, with adiam- 
DiAMETER. — eter of ^5^^ of an inch. The plasma of the 
PLASMA. — blood is composed of water holding im- 
portant organic and inorganic principles in solution. It 
is known as the liquor sanguinis and has a specific grav- 
FUNCTION OF CORPUSCLES._ity of 1028. The 
function of the red corpuscles is to carry the gases. The 
COLORING MATTER OF RED CORPUSCLES.— 
coloring matter of the red corpuscles is haemaglobine. 
PLASMINE. — -Plasmine is composed of fibrine and met- 
ALBUMEN. — albumen. The albumen of the blood 
is formed by the union of serine and metalbumen. 



THE BLOOD, 45 

COAGULATION.— The coagulation of the blood 
is due to the formation of fibrine. and in the process 
CLOT. — the blood divides into a clot and serum. 
The clot or crassamentum is composed of corpuscles^, 
red and white, and fibrine, also retaining about one- 
BUFFY COAT.— fifth of the serum. The buffy coat 
of the clot is due to the white corpuscles. The se- 
SERUM. — rum retains all the elements of the plasma 
except those of fibrine. 



CIRCULATION OF THE BLOOD. 



CIRCULATION OF THE BLOOD.—Harvey dis- 
covered the circulation of the blood in 1616 ; Michael 
Servetus the pulmonary circulation in 1553: and 
Malpighi, the capillary circulation in 1661. 

THE HEART. — The heart is a pear-shaped organ 
WEIGHT. — situated in the left thoracic cavity. It 
weighs in the female from eight to ten ounces, and 
CAVITIES, — from ten to twelve ounces in the male. It 
has four cavities, — a right and left auricle, and a right 
PERICARDIUM— .and left ventricle. . It is enveloped 
in a fibrous sac called the pericardium. Its cavities 
ENDOCARDIUM. — are lined by a smooth serous 
membrane called the endocardium. The right auricle 
AURICULAR APPENDIX.— has an appendix, re- 
sembling the ear of a dog, known as the auricular 
appendix. The openings between the auricles and 

AURICULO-VENTRICULAR O P E NINGS.— the 

46 



THE CIRCULATION OF THE BLOOD, 47 

ventricles are known as the auriculo- ventricular open- 
AURICLES. — ings. The walls of the auricles are 
thinner than those of the ventricles, and are composed 
of muscular fibres in two layers, — the outer, being 
common to both, and the inner, proper to each. Al- 
though the walls are involuntary in their action,, they 
are composed of striated fibres. The walls of the 
VENTRICLES. — left ventricle are thicker than those 
of the right. The ventricles constitute the bulk of the 
heart, and the arrangement of their muscular fibres is 
similar to that in the auricles. The inner surface of 
COLUMN.E: CARX.E.—the ventricles is marked by 
pecuhar fleshy ridges and papillae, called column te 
CHORDAE TENDIN.E. — carna?, and passing from 
them to the auriculo-ventricular valves are tendinous 
cords, known as chordae tendinae. The roughened 
surfaces of the auricles are known as the muscular 
TRICUSPID VALVES.— pectinati. The three leaf- 
lets closing the auriculo-ventricular opening on the 
right side are called the tricuspid valves. The valves 
PULMONIC VALVES. — closing the pulmonary art- 
ery are the pulmonic, semilunar, or sigmoid valves. 
MITRAL VALVE. — The mitral or bicuspid valve is 
composed of two leaflets, and closes the left auriculo- 



48 THE CIRCULATION OF THE BLOOD, 

AORTIC VALVES.— ventricular orifice. The valves 
closing the aorta are known as the aortic, semilunar, 
or sigmoid valves. The sinuses of Valsalva are three 
SINUSES OF VALSALVA.— pouches which occur 
behind the semilunar valves at the aorta. The corpora 
CORPUS ARANTIUS.— Arantia are little bodies 
found on the semilunar valves, aiding in their closure. 
MOVEMENTS OF THE HEART.— The heart is 
twisted from left to right, in systole, and untwisted in 
diastole, becoming hardened at each systole. The dil- 
DIASTOLE. — atation of the cavities of the heart is 
SYSTOLE. — called diastole ; their contraction, sys- 
IMPULSE. — tole. The heart is not situated in direct 
contact with the walls of the thorax, but during systole 
is forcibly impressed against them constituting impulse. 
FORCE OF THE HEART— The force of the left 
auricle is fifty-one and a half pounds. There is a 
REGURGITATION OF BLOOD.— slight regurgita- 
tion of blood through the tricuspid valve, but this is 
not permitted by the mitral. There are two sounds 
SOUNDS OF THE HEART.— of the heart;— the 
long, dull sound, and the short, quick sound, — between 
them is an interval of silence. The first of these 
sounds is produced by the impulse, the closure of the 



THE CIRCULATION OF THE BLOOD. 49 

auriculo-ventricular valves, and the rush of the blood 
over the roughened walls of the heart cavities; the 
other, is due to the closure of the aortic and pulmonic 
FREQUENCY— semilunar valves. The heart in the 
adult male makes about seventy pulsations in a min- 
ute, and a few more in the female. The frequency of 
course is modified by age, digestion, posture, muscular 
exertion, temperature, respiration, etc. 

ROUTE OF THE CIRCULATION IN THE 
HEART. — The blood is received from the vena cava 
ascendens and descendens into the right auricle ; and 
is passed from the right auricle through the auriculo- 
ventricular opening, closed by the tricuspid valve, into 
the right ventricle ; from the right ventricle it passes 
through the pulmonary artery, closed by the pulmonic 
valves, to the lungs ; from there it is returned by the 
pulmonary veins to the left auricle ; from the left auri- 
cle it passes through the auriculo-ventricular opening, 
closed by the mitral valve, into the left ventricle ; 
from the left ventricle it passes through the aorta, 
closed by the aortic valves, to the system at large. The 
CORONARY SYSTEM.— blood in the heart does not 
nourish it ; but it receives its supply by the coronary 
arteries, and returns that blood by the coronary veins, 



go THE CIRCULATION OF THE BLOOD, 

which taken together constitute the coronary system. 

ARTERIES. — The branches of arteries, except the 
intercostal, are given off at an acute angle. Arteries 
FUNCTION. — convey red or arterial blood from the 
COATS. — heart, and have three coats: — an outer ot 
white or inelastic fibrous tissue ; a middle of yellow 
elastic tissue ; and an internal, serous coat. Owing 
ELASTICITY. — to their elasticity, the arteries are dis- 
tended during systole. At each contraction of the 
LOCOMOTION. — heart the arteries are lengthened, and 
many of them undergo some locomotion. The sensa- 
PULSE. — tion felt at each beat of the heart by placing 
the finger over an exposed artery is called the pulse. 

CAPILLARIES. — The capillaries are the tubes con- 
necting the arteries and the veins ; they have but a 
single coat, and in them takes place the interchange of 
gases. 

VEINS. — The veins collect the blood from the ar- 
teries and convey it back to the heart as venous or 
COATS. — dark blood. They have three coats. Through- 
VALVES. — out the veins are valves, situated just below 
the points where smaller veins empty into the larger^ 
thus presenting an obstacle to the passage of the blood 
in the wrong direction. The cause of the venous cir- 



THE CIRCULATION OF ThE BLOOD, 51 

dilation is the pressure of the blood from behind, — 
the vis a tergo ; and also the suction power of the 
heart, — the vis a fronte. The general average of the 
GENERAL RAPIDITY OF THE CIRCULATION, 
—duration of the circuit of the blood through the en- 
tire system is twenty-three seconds. The vessels them- 
VASA VASORUM. — selves are nourished by smaller 
ones known as the vasa vasorum. 







RESPIRATION. 



RESPIRATION. — Respiration consists in an inter- 
change of gases, and is the process by which tissues 
and organs receive and appropriate oxygen. The 
essential conditions of respiration in animals are ; — a 
current of air and a current of bloody separated by a 
thin membrane which will allow the passage of the 
gases. The anterior opening into the pharynx leads 
LARYNX. — to the larynx, and is the commencement 
of the respiratory passages. The larynx is a cartilagin- 
ous box, and across its superior opening are the vocal 
chords, — four in number. The two superior are false, 
and the two inferior are true vocal chords, being con- 
cerned in the production of voice. The opening be- 
RIMA GLOTTIDIS.— tAveen these chords is known 
as the rima glottidis. The epiglottis is the cartilage 
EPIGLOTTIS. — that serves to close the larynx during 

deglutition. From the larynx to the lungs is a tube, 

52 



RESPIRA TION. 



53 



TRACHEA. — four and a half inches m length and 
three-quarters of an inch in diameter, known as the 
trachea. It is composed of from sixteen to twenty 
cartilaginous rings, which are cartilage in the anterior 
two-thirds; — the posterior one-third of each being 
fibrous tissue. In the chest the trachea divides into 
BRONCHI. — t^vo bronchi, the right being the shortest 
and largest. The bronchi divide into bronchioli, and 
these end in the air cells. The lungs and air passages 
MUCOUS MEMBRANE. — are lined by mucous mem- 
PARENCHYMA. — brane. The nssue of the lungs is 
LUNGS. — known as their parenchyma. The lungs 
are irregular cones situated in the thoracic cavity. Ar- 
terial blood for their nourishment is conveyed to them 
by the bronchial arteries. 

INSPIRATION. — Inspiration is the process by 
which air is taken into the lungs. The muscles used 
are those of the upper portion of die chest, together 
with the intercostals and diaphragm. Expiration is 
EXPIRATION. — the process by which air is forced 
out of the lungs, and is accomplished by the elasticity 
of the kmgs and thoracic walls, aided by certain mus- 
cles which diminish the size of the chest. The fre- 
FREQUENCY OF RESPIRATION.— quency of 



54 



RESPIRA TION. 



respiration varies with the time of life, being in the 
adult, one respiration to every four beats of the heart 
or from sixteen to eighteen in a minute. Snoring is a 
SNORING. — peculiar sound caused by the flapping of 
the velum pendulum palati between two currents of 
air; — one from the mouth, and the other from the 
RESIDUAL x\IR. — nose. Residual air is that which 
cannot be expelled by a forced expiration, and is one 
hundred cubic inches. Reserve air is that which 
RESERVE AIR. — remains after an ordinary expira- 
tion, but can be expelled by a forced one, and is one 
hundred cubic inches. Tidal or breathing air is that 
TIDAL AIR. — which is changed by an ordinary in- 
spiration and expiration, and is twenty cubic inches. 
COMPLEMENTAL AIR.— Complemental air is the 
excess over the ordinary breathing air which may be 
drawn into the lungs by a forcible inspiration, and is 
one hundred and ten cubic inches. The extreme 
BREATHING CAPACITY.— breathing capacity of 
the lungs is two hundred and thirty cubic inches. 
Some of the air inspired is lost in respiration. 

COMPOSITION OF AIR. —Air is a mixture of 
oxygen and nitrogen in the proportion of one to four. 
The carbonic acid in respired air comes from the 



RESPIRA TION. 



55 



venous blood, and a certain amount of vapor always 
accompanies it as a product of respiration. A small 
quantity of nitrogen is exhaled by the lungs. The 
CHANGES IN THE BLOOD IN RESPIRATION. 
— blood is changed from venous to arterial in its pass- 
age through the lungs. This is shown by a change in 
color from dark to bright red, and is caused by its 
giving off carbonic acid and taking up oxygen. Car- 
bonic acid exists in solution in the plasma, while the 
other gases in the blood, and particularly oxygen, are 
in feeble combination with the coloring matter of the 
RESPIRATORY SENSE.— red corpuscles.* Respi- 
ration takes place in response to a demand for oxygen 
on the part of the system known as the respiratory 
CUTANEOUS RESPIRATION.— sense. A certain 
amount of oxygen is absorbed by the skin, and a 
larger proportion of carbonic acid is exhaled. Asphyxia 
is death caused by cutting off the supply of oxygen to 
the system. It is the result of the fixation of the car- 
bonic acid gas preventing the introduction of oxygen, 
and not due to any poisonous effects of that gas. 



SECRETION. 



SECRETION. — Secretion is intimately connected 
with nutrition and embraces the processes in which there 
is a separation of materials from the blood, or a for- 
mation of a new fluid out of matters furnished by it. 
Secretions are generally homogeneous fluids without 
formed anatomical elements, and are produced by 
ORGANS. — membranes, tubes, or glands. The structure 
SEROUS MEMBRANES.— of serous membranes is 
very simple ; — they have a dense tissue of fibres cov- 
ered by a single layer of pavement epithelium. They 
MUCOUS MEMBRANES.— line close cavities. Mu- 
cous membranes are attached by areolar tissue to the 
subjacent parts and are either covered by pavement or 
FUNCTION. — by columnar epithelium. They line open 
cavities. Mucus allows the parts moistened by it to 
move freely and modifies absorption. The cutaneous 

SEBACEOUS FLUIDS— surface is lubricated by an 

56 



SECRETION. 57 

oily secretion called sebum, produced by sebaceous 
glands which are either simple or compound racemose. 
CERUMINOUS GLANDS.— Ceruminous glands se- 
crete a waxy matter, called cerumen, of a yellowish 
color and bitter taste. The mammary glands are re- 
MAMMARY SECRETION.— markable organs in the 
economy, and have an areolar, or darker portion, 
encircling the nipple. All the important and charac- 
teristic materials in the milk are formed in the sub- 
AMOUNT. — stance of the gland. About two or three 
pints of milk can be secreted by the average woman 
SPECIFIC GRAVITY. — in a day. The specific gravity of 
milk is from 1032 to 1046. The first fluid drawn from 
COLOSTRUM.— the breast after delivery is called 
colostrum and has a specific gravity above that of 
milk, being from 1046 to 1060. 




EXCRETION, 



EXCRETION. — Excretions are generally dis- 
charged from the body, and all their elements pre-ex- 
ist in the blood either in the condition in which they 
are discharged, or in some slightly modified form. 

THE SKIN. — The skin is an important structure of 
the body, and possesses a variety of functions; — 
EXTENT. — among them is excretion. The cutaneous 
surface of a good sized man is sixteen square feet. 
THICKNESS. — The skin varies in its thickness and exists 
usually in two layers, — the true skin, or cutis vera, 
derma, or corium ; and the epidermis, cuticle, or 
scarf-skin. The epidermis serves as a protection to 
NAILS AND HAIR. — the more delicate true skin. 
The nails and hair are appendages of the epidermis, 

NAILS. — The nails are situated on the dorsal sur- 
faces of the distal phalanges of the fingers and toes, 
and serve to protect these parts. In prehension they 

58 



EXCRETION. 



59 



ROOT. — are quite important to the fingers. The root 
of the nail is thin and soft and is received in a fold 
BODY. — of the skin. Its iDody extends from the fold 
of the skin \o the free border, and is closely adherent 
HAIRS. — by its under surface to the true skin. Hairs 
varying greatly in size and development cover every 
portion of the cutaneous surface except the palmar 
surfaces of the hands, feet, toes, and fingers; the lips; 
upper eyelids ; and the lining of the prepuce and glans 
VARIETIES. — penis. They are divided into short and 
stiff, long, fine and downy. The long and soft hairs 
are found on the head, the face of the adult male, 
around the genital organs, under the arms, upon the 
breast and over the general surface of the body of the 
male. The short and stiff are found in the nostrils, 
on the edges of the eyelids, and upon the eyebrows. 
The short, soft, downy hairs are found on all the gen- 
eral surface not occupied by the long hairs. The 
ROOTS. — roots of the hair are imbedded in follicular 
SHAFT. — openings in the skin. The shaft is composed 
• of a medullary portion, covered by quadrangular 
scales, known as the epidermis of the hair or cortical 
portion. The medullary portion sometimes becomes 
filled with air giving rise to a change of color. Hairs 



6o EXCRETION. 

FUNCTION. — act as a protection to the surfaces upon 
which they are placed. 

SUDORIPAROUS GLANDS.—The most numer^ 
ous and most important glands of the skm are those 
secreting the sweat, and with few exceptions are every- 
where placed upon its surface. The evaporation from 
the skin tends to regulate the temperature of the body, 
and about two pounds of sweat are thrown off in 
twenty- four hours, the specific gravity of which is 
1003 to 1004. The action of the skin is vicarious 
with the kidneys. . 

URINE. — The urine is an excrementitious fluid 
eliminated by the kidneys, which are symmetrical 
organs, situated in the upper and posterior part of the 
KIDNEYS. — abdomen. They are shaped like beans, 
with the central portion of the concave side, the 
hilum, looking toward the spinal column. Each 
WEIGHT. — kidney weighs from four to six ounces, and 
the left is always a little heavier than the right. A 
PELVIS. — section of the kidney shows a cavity at the 
hilum known as the pelvis. Each kidney is composed 
CORTICAL SUBSTANCE. — of a cortical substance, and a 
pyramidal or medullary substance. The cortical is 
softer than the pyramidal substance. The medullary 



EXCRETION. 6i 

MEDULLARY SUBSTANCE. — substance is arranged in the 
form of pyramids called the pyramids of Malpighi, 
and made up of tubes called the tubuli uriniferi. At- 
tached to these tubes are convoluted ones, which pass 
to the Malpighian bodies situated in the cortical por- 
BLOODVEssELS. — tion of the kidney. The renal artery 
enters at the hilum, bringing blood to the kidney, 
which the renal veins remove. 

PRODUCTION OF URINE.—Urea and other ex- 
crementitious constituents of the urine are produced 
by the process of disassimulation in the various tissues 
and organs of the body, being taken up by the blood 
and simply separated from it by the kidneys. Increase 
in the pressure of the blood in the kidneys increases 
URETERS. — the flow of urine. The excretory ducts 
of the kidneys are known as the ureters, and commence 
with the pelvis at the hilum. They are membraneous 
tubes of the diameter of a goose quill, and from sixteen 
to eighteen inches in length, passing from the kidneys 
COATS — to the bladder. They have three distinct 
coats ; — an external, fibrous ; a middle, muscular ; 
and an internal, mucous coat. The bladder which 
THE BLADDER. — serves as a reservoir for the urine, 
when empty is of triangular form, but when filled be- 



62 EXCRETION, 

comes of an ovoid shape, and will hold normally 
COATS. — about a pint. It has three coats, — an exter- 
nal, peritoneal ; a middle, muscular ; and an internal, 
URETHRA.— mucous coat. The bladder is emptied 
by a tube known as the urethra. 

URINE. — The urine is of a yellowish or amber 
QUANTITY. — color, and about fifty fluid ounces are 
SPECIFIC GRAVITY. — voidcd in a day, being of a specific 
REACTION. — gravity of 1015 to 1025. Its reaction is 
usually acid although it depends upon the kind of 
food, and therefore under circumstances may be alka- 
UREA. — line. Urea, the most important of the uri- 
nary constituents, is one of the few organic proximate 
principles that the chemist can produce by synthesis. 
It crystallizes in long, four sided, colorless, transparent, 
neutral prisms ; and is produced in the nitrogenized 
parts of the organism. Uric and hippuric acids, cre- 
atine and creatinine, together with many inorganic 
constituents, such as chlorides, sulphates, and phos- 
phates, are found in the urine. The composition of 
urine is influenced by sex, season of the year, time of 
day, digestion, temperature, sleep, exercise, etc. 

THE LIVER. — The liver is the largest gland in 
SITUATION.— the body, and lies just below the dia- 



EXCRETIOM, 63 

phragm in the right hypochondriac region, and 
WEIGHT. — weighs about four and a half pounds. It is 
CAPSULE OF GLISSOX.— covered by a membrane 
called the capsule of Glisson, and in substance is made 
up of an innumerable number of irregular lobules. At 
PORTAL VEIN. — the transverse fissure, the portal 
vein, collecting blood from the abdominal organs ; the 
hepatic artery, a branch of the coeliac axis, and the 
hepatic duct, penetrate the substance of the liver. The 
portal vein is the larger of the two bloodvessels. The 
INTERLOBULAR VEINS.— branches of the portal 
vein going between the lobules, are known as the in- 
terlobular veins. From the interlobular veins come 
LOBULAR VEINS. — eight to ten branches, penetrat- 
ing the lobules and known as the lobular veins. These 
INTRALOBULAR VEINS.— empty in the centre of 
each lobule into a vein coming from it, known as the 
intralobular vein. It pours its contents into the sub- 
SUBLOBULAR VEINS.— lobular veins, and they in 
HEPATIC VEINS. — turn empty into three hepatic 
veins, which discharge the blood from the liver into 
HEPATIC ARTERY.— the vena cava ascendens. The 
hepatic artery brings blood to nourish the structure of 
HEPATIC DUCT.— the liver. The hepatic duct 



64 EXCRETION. 

carries away the bile, and is the result of the union of 
two ducts; — one from the right, and the other from 
the left lobe of the liver. 

GALL BLADDER —The gall bladder is a pear- 
shaped sac, four inches in length, lying under the liver 
CYSTIC DUCT.— and emptied by a spiral duct,— the 
cystic duct. The spiral condition aids the ascent of 
COMMON DUCT.— the bile against gravitation. The 
hepatic duct and the cystic duct unite to form the 
ductus communis choledochus, which opens into the 
intestine. 

FUNCTION OF LIVER. —The liver is a secreting 
and excreting organ, and a ductless gland. It secretes 
AMOUNT OF BILE SECRETED— two and a half 
pounds of bile in a day, which during the intervals of 
THE BILE. — digestion is stored in the gall bladder. 
Bile is a viscid, dark yellowish green secretion. That 
coming from the gall bladder is the darkest in color. 
It has a specific gravity of from 1020 to 1026, and 
contains two classes of constituents, — elements of se- 
cretion, which are absorbed ; and an element of excre- 
tion, which is discharged by the faeces in an altered 
CHOLESTERINE.— form, namely, cholesterine. 
BILIVERDINE. — Biliverdine is the coloring matter ot 



EXCRETION, 65 

the bile. x\s sugar is always found in the blood of 
the hepatic veins, it is believed to be formed by the 
liver, and that it is independent of the sugar and starch 
taken as food. This sugar forming function is sup- 
posed to be due to a material found in the substance 
of the liver called glycogen. It is this production of 
sugar that classes the liver among the ductless glands. 

DUCTLESS GLANDS.— The ductless glands in- 
clude the spleen, the supra-renal capsules, the thyroid 
and thymus glands, the pituitary body, and the pineal 
gland. 

THE SPLEEN.— The spleen is situated in the left 
hypochondriac region at the cardiac extremity of the 
stomach, and is shaped like the tongue of a dog, hav- 
ing a vertical fissure, called the hilum, which gives 
passage to the veins and nerves. It has in its sub- 
MALPIGHIAN BODIES.— stance about ten thousand 
bodies known as Malpighian bodies, or splenic corp- 
uscles. 

SUPRA-RENAL CAPSULES.— The supra-renal 
capsules are small, triangular, flattened bodies, capping 
the kidneys at their superior anterior end. They are 
about an inch and a half in length, of a whitish yellow 
color, and composed of two substances ■ — a cortical, 



66 EXCRETION. 

and a medullary. The bronzing of the skin in Addi- 
son's disease is due to a structural change in these 
bodies. 

THYROID GLAND.—The thyroid gland is at- 
tached to the lower part of the larynx and is of a 
brownish red color. It is formed of two lateral lobes, 
and is larger and more prominent in the female than 
THYMUS GLAND.— in the male. The thymus 
gland is found only in early life, as in the adult the 
organ is wanting, traces only of its previous existence 
remaining. It is situated partly in the thorax and 
partly in the neck, and is of a grayish color. 

PITUITARY BODY AND PINEAL GLAND.— 
The pituitary body and pineal gland are situated at the 
base of the brain ; — the former is ovoid in shape, of a 
reddish gray color, and situated on the sella turcica of 
the sphenoid bone : the latter is placed just behind the 
posterior commissure of the brain, and is a conical 
body about one-third of an inch in length. Nothing 
FUNCTION OF DUCTLESS GLANDS.— is known 
of the function of these ductless glands. 



NUTRITION. 



NUTRITION. — Nutrition is the process by which 
the waste of the tissues and fluids of the body is re- 
paired by the appropriation of new material. All the 
INORGANIC PRINCIPLES.— inorganic principles 
taken in with the food, generally pass out of the or- 
ganism in the form in which they enter. About 
twenty- one inorganic principles exist in the human 
body. They are, — oxygen, hydrogen, nitrogen, car- 
buretted hydrogen, sulphuretted hydrogen, water, 
chloride of sodium, chloride of potassium, phosphate 
of lime, carbonate of lime, carbonate of soda, carbon- 
ate of potassa, phosphate of magnesia, phosphate of 
soda, phosphate of potassa, sulphate of soda, sulphate 
of potassa, sulphate of lime, hydrochlorate of ammo- 
nia, carbonate of magnesia, and bicarbonate of soda. 
NITROGENIZED PRINCIPLE S.— Nitrogenized 

principles of food have for their basis, — carbon, 

67 



68 NUTRITION, 

hydrogen, nitrogen, and oxygen; and go toward 
making tissue in place of that which has been de- 
EXERCISE. — stroyed. Nutrition is greatly influenced 
by exercise and diet. The non-nitrogenized elements 
NON-NITROGENIZED PRINCIPLES— are in 
themselves incapable of meeting the nutritive demands 
of the system, and are either consumed without form- 
ing part of the tissues or deposited as fat. 

ANIMAL HEAT.— The process of nutrition is 
always accompanied by the development of heat. 
The normal temperature of man is 98^ Fah. The 
general temperature of the body varies with extreme 
changes in climate, and the limit of this variation con- 
sistent with life is from 83° to 107° Fah. There is a 
variation in temperature in different parts of the body, 
and also at different periods of life. The temperature 
is increased by exercise. No portion of the organism 
is the seat of the production of heat, but every portion 
produces a part, as it is the necessary consequence of 
the processes of nutrition. Respiration, being one of 
the nutrient processes, has an intimate connection 
with calorification. The temperature of man can be 
equalized by the use of clothing. When from any 
cause there is a tendency to an undue elevation of 



NUTRITION. 



69 



temperature, it is corrected by the evaporation of 
moisture produced by the sudoriparous glands. Man 
has thus been enabled to endure a temperature from 
400° to 600° Fah. 



MOVEMENTS. 



MOVEMENTS— In some of the lowest forms of 
life we have movements of elongation and retraction, 
CILIARY MOVEMENTS— called amoeboid. The 
epithelium covering certain of the mucous membranes 
is provided with hair like processes upon the free por- 
tion of the cells, called cilia ; and these are in motion 
from the beginning to the end of life, producing cur- 
rents upon the surfaces to which they are attached. 
The direction of the motion, is from within, outward. 
No reason has been given for the movements, they not 
being due to muscular or nervous intervention. Cer- 
ELASTIC MOVEMENTS.— tain movements of the 
body are due to the action of elastic ligaments or mem- 
branes. There are three kinds of elastic tissue ; — 

small fibres, — found in the lungs ; in the true skin, in 

70 



MOVEMENTS, 7 1 

ligaments, etc. : large ribbon-shaped fibres, — found 
in ligaments; and the large flat fibres having many 
anastomoses. 

MUSCULAR MOVEMENTS.— Muscular move- 
ments are divided into the voluntary and involuntary. 
VOLUNTARY MUSCLES.— The voluntary muscles 
are invariably attached by their two extremities to 
movable parts, and are made up of red striated fibres 
called primitive fasciculi. A primitive fasciculus runs 
PRIMITIVE FASCICULUS.— the entire length of 
the muscle, and is enclosed in its own sheath, known 
as the sarcolemma or myolemma. The involuntary 
INVOLUNTARY MUSCLES.— muscles generally 
exist in sheets or membranes, made up of smooth 
fibres, excessively pale, very finely granular, and 
spindle-shaped, with a narrow nucleus in the centre. 
CONNECTIVE TISSUE.— In muscles there is a 
fibrous structure which holds a number of primitive 
fasciculi in a bundle, and sometimes encloses these 
bundles to make a larger muscle ^ This fibrous tissue 
is the perimysium, now called connective tissue, and 
has an excessively thin and wavy fibre. 

PROPERTIES OF MUSCLES.— Muscles have the 
property of elasticity, tonicity, sensibility, and con- 



J 2 MOVEMENTS. 

ELASTICITY.— tractility Their elasticity is brought 
into play in opposing sets of muscles, and by virtue of 
it one will retract when the opposing force of the other 
TONICITY. — is removed. Their tonicity is an in- 
sensible contraction by which the action of opposing 
muscles is balanced when both are in a state of repose. 
SENSIBILITY. — The sensibility of muscles is ex- 
pressed in the sense of fatigue, and in their appreci- 
ation of weight and resistance. Their contractility 
CONTRACTILITY.—enables them to contract, and 
to exert a certain amount of mechanical force under 
proper stimulus. During muscular contraction the 
MUSCULAR CONTRACTION.— fibres harden and 
shorten. The actual volume of the muscle remains 
the same, although increased in thickness in propor- 
LOCOMOTION. — tion to the shortening. Locomo- 
tion is produced by muscles acting upon bones, liga- 
ments, etc. 

BONE. — Every bone is marked by microscopic 
cavities and canals of varying size. These cavities 
STRUCTURE. — Contain bone corpuscles, and the larger 
canals serve for the passage of blood vessels. Many 
bones have in the centre a medullary cavity filled with 
marrow. Bones are of two kinds of structure,— the 



MOVEA/EiVTS. 73 

compact or solid, and the spongy or cancellated ; and 
are covered by a membrane called the periosteum. 
HAVERSIAN CANALS.— The compact structure is 
filled with irregular microscopic excavations called 
LACUNA. — lacunae, arranged in concentric lamellae 
around central tubes called Haversian canals. Pass- 
CANALICULI. — ing from ihe lacunas to each other 
and to the Haversian canals are smaller tubes termed 
CARTILAGE. — canaliculi. Cartilage is a whitish ■ 
substance, not covered by a membrane, and made up 
either of a homogeneous fundamental substance filled 
with cartilage cells, or of fibrous tissue filled with the 
same. 

VOICE. — The voice is produced in the larynx and 
modified by the mouth and nasal passages. The vccal 
VOCAL CHORDS. — chords are in two pairs, stretched 
across the superior opening of the larynx from before 
backwards. The superior or false are not concerned 
in the production of the voice. The inferior or true 
chords are attached together to the middle of the 
thyroid cartilage, which is immovable : and posteriorly 
to the movable arytenoid cartilages. The muscles of 
MUSCLES OF THE LARVNX.— the larynx are di- 
vided into the extrinsic and intrinsic. The extrinsic 



74 



MO VEMENTS. 



muscles are attached to the outer surface of the larynx, 
and to adjacent organs; while the intrinsic are at- 
tached to the larynx itself, and by their action are 
capable of modifying the voice. 

MUSCLES MODIFYING THE VOICE._The 
muscles concerned in modifying the voice are, — the 
crico- thyroids, the arytenoid, the lateral crico-aryte- 
noids, and the thyro-arytenoids. The crico-thyroid 
CRICO-THYROID MUSCLES.—muscles arise from 
the anterior and lateral portions of the cricoid cartilage, 
and are inserted into the inferior border of the thyroid 
ARYTENOID MUSCLE.— cartilage. The arytenoid 
muscle fills up the space between the two arytenoid 
cartilages, being inserted into their posterior borders. 
LATERAL CRICO- ARYTENOID. —The lateral cri- 
co-arytenoids are situated in the interior of the larynx, 
arising from the sides and superior borders of the 
cricoid cartilage, and becoming inserted into the base 
of the arytenoid cartilages. The thyro- arytenoid 
THYRO-ARYTENOID MUSCLES.—muscles arise 
from the crico-thyroid membrane and the thyroid car- 
tilage, and are inserted into the arytenoid cartilages. 
QUALITY OF VOICE The variations in the qual- 
ity of voice depend upon differences in size and form 



MOVEMENTS. 



75 



of the larynx and vocal chords, the trachea being an 
assessory vocal organ. 

SPEECH. — Speech is the production of articulate 
LANGUAGE. — ^sounds. Language is a conventional 
series of sounds made for the purpose of conveying 
certain ideas. 



^mm^ 



NERVOUS SYSTEM. 



NERVOUS SYSTEM._A nervous system is com- 
posed of a single ganglion, or of two or more ganglia 
joined together. There are two kinds of nervous 
matter, — nerve cells, and nerve fibres ; or the gray or 
vesicular, and the white or tubular. A union of white 
A GANGLION. — and gray matter is called a ganglion. 
THE GRAY MATTER._The gray matter is com- 
posed of cells having a distinct nucleus and nucleoli, 
FUNCTION. — and is the only kind of nervous matter 
capable of generating the so-called nervous force. On 
these cells are prolongations known as the poles, and 
the cells possessing them are called caudate. If they 
have one prolongation they are known as a unipolar 
cell ; if two, as a bipolar ; if three or more, as a mul- 
tipolar ; or when existing without any, as apolar cells. 

THE WHITE MATTER.—The white nervous matter 

76 



THE NER VOUS S YSTEM, yy 

is tubular in its appearance, and serves only as a con- 
ductor, being incapable of generating nervous force. 
It exists in two varieties, — the medullated, and the 
non-medullated fibres. It shows on examination an 
NEURILEMMA. — outer covering, — the neurilemma; 
WHITE SUBSTANCE.— a substance beneath,— the 
AXIS-CYLINDER.— white substance of Schwann; 
ULTIMATE NERVE FIBRE.— and inside of all the 
axis-cylinder. The latter is the essential element of 
the tissue, and passing through it are the ultimate nerve 
MEDULLATED FIBRES.— fibres. Medullated fibres 
are those which have the white substance of Schwann 
between the neurilemma and the axis- cylinder ; while 
NON-MEDULLATED FIBRES. —the non-medul- 
lated fibres are simple prolongations of the axis-cylinder 
of the medullated fibres. An ultimate nerve fibre runs 
from its beginning to its end without uniting with any 
other, although it may pass from the sheath of one 
nerve into that of another. 

MOTOR AND SENSORY NERVES. —Nerves 
conveying motor stimulus are motor nerves. Sensory 
ones convey sensory impressions. The motor nerves 
TERMINATION OF NERVES.— terminate in the 
voluntary muscles by granular plates ; in the involun- 



78 THE NERVOUS SYSTEM, 

tary, by forming a plexus ; while nerves sent to glands 
terminate in a somewhat similar manner to those in 
involuntary muscles. The sensory nerves terminate 
either by free extremities, by passing into hair fol- 
licles, or by corpuscles constructed for the purpose, 
viz. — the corpuscles of Pacini, tactile corpuscles, and 
CORPUSCLES OF PACINI.— terminal bulbs. The 
corpuscles of Pacini or of Vater are egg-shaped, and 
consist of several layers of connective tissue enclosing 
a central bulb, in which is placed the terminal end of 
the nerve. These corpuscles are situated beneath the 
TACTILE CORPUSCLES.— true skin. The tactile 
corpuscles are found in parts endowed with tactile sen- 
sibility, and in the substance of the papillae of the 
skin. They are oblong in shape and have the nerve 
fibres in a spiral bundle. The terminal bulbs are 
TERMINAL BULBS. — somewhat similar to the tac- 
tile corpuscles in structure, but are much smaller. 

COMPOSITION OF NERVOUS TISSUE— 
Nerve substance is principally made up of protagon, 
neurine, and fatty matters combined with phosphorus. 
REGENERATION OF NERVOUS TISSUE.— It 
can be regenerated with the re-establishment of func- 
NERVOUS IRRITABILITY.— tion. Nervous irri- 



THE NER VO US S YSTEM. 79 

tability is that condition by which nerves respond to, 
and conduct stimulation. This condition of the motor 
nerve is distinct from that of the sensory; — in one it 
may be destroyed, and in the other remain intact. 
NERVOUS FORCE.—Nervous force is a peculiar 
one, and generated by the gray substance, nothing 
being known of its essential nature except that it is not * 
identical with electricity. The rate of nervous con- 
RAPIDITY OF CONDUCTION.— duction is one 
hundred and eleven feet per second, being the same in 
ELECTRICITY. — motor and sensory nerves. Elec- 
tricity is the best means of artificially exciting the 
nerves. 

DIVISIONS OF THE NERVOUS SYSTEM.--- 
The nervous system is divided into three great divis- 
ions; — the cerebro-spinal, the true spinal, and the 
great sympathetic. The cerebro-spinal or voluntary 
THE CEREBRO-SPINAL SYSTEM. —nervous sys- 
tem includes the brain and spinal cord, with the 
nerves directly connected with these centres. The 
THE TRUE SPINAL SYSTEM— true spinal, reflex 
or involuntary system is composed of the spinal cord 
as a centre, and the nerves arising from it. The 
THE GREAT SYMPATHETIC SYSTEM. ^great 



8o THE NER T ^O US S YS 7 EM, 

sympathetic or ganglionic system is composed of a 
chain of gangha, situated on either side of the spinal 
column, and joined together at the os coccyx. 

THE BRAIN. — The average weight of the brain in 
weight: — man is forty-nine ounces ; in woman, forty- 
SPECiFic GRAVITY. — four ounccs. Its specific gravity 
is 1036 ; that of the gray matter being 1034 ; and of 
the white, 1040. In the brain the white matter is 
found on the inside : and the gray, upon the outside. 
DIVISIONS. — The brain is divided into the cerebrum, 
the cerebellum, the pons varolii, and the medulla ob- 
longata. It is covered by three membranes, — the dura 
mater, the arachnoid, and the pia mater. It is situated 
in the brain case, an expanded vertebra. The dura 
DURA MATER. — mater is closely adherent to the 
bones of the brain case. The arachnoid membrane is 
ARACHNOID MEMBRANE.—serous, and exists in 
PLA MATER. — two layers. The pia mater is a vas- 
cular membrane. 

THE CEREBRUM.— The cerebrum is divided into 
two hemispheres, — a right and a left; and constitutes 
four-fifths of the encephalic mass. It is thrown into 
convolutions for the purpose of increasing the gray 
FUNCTION, — matter, and presides over the intellectual 



THE NER VO US S YS TEM, g I 

faculties. The faculty of articulate language is restricted 
to the anterior lobes of the cerebrum. 

THE CEREBELLUM.— The cerebellum lies be- 
neath the posterior lobes of the cerebrum and presides 
FUNCTION. — over co-ordination of muscular move- 
CORPORA STRIATA.— ments. At the base of the 
brain, partly imbedded in the white substance of the 
cerebral hemispheres, are two pear-shaped bodies, 
made up of alternate striae of white and gray matter, 
called the corpora striata, their narrow extremities be- 
ing extended backward. Very little is known about 
their function, — they seem to be connected with the 
motor nerves. Between the narrow extremities of the 
OPTIC THALAMI. — corpora striata are the optic 
thalami, — oblong bodies, having an internal mixture 
of gray and white matter, and seeming to be connected 
with the sensory nerves. The tubercula quadrigemina 
TUBERCULA QUADRIGEMINA.— are oblong 
bodies, situated two on each side, just below the third 
ventricle. The larger and anterior two are called the 
nates : the posterior, the testes. They are composed 
of white and gray matter, and are the main points of 
FUNCTION. — the origin of the optic nerves, presiding 
over the sense of sight. 



82 THE NER VO US S YSTEM. 

PONS VAROLII. —The pons or tuber annulare is 
white externally, but has gray matter on the inside. It 
acts as a conductor of sensory impressions and motor 
FUNCTION. — stimulus to and from the cerebrum. Be- 
ing able to act as a nervous centre and give rise to vol- 
untary movements, it probably regulates the move- 
ments of progression and station. 

MEDULLA OBLONGATA.— The medulla oblon- 
gata is the oblong enlargement that connects the spinal 
cord with the brain. Like the cord it has an anterior 
and posterior median fissure. Continuous with the 
ANTERIOR PYRAMIDS. — anterior columns of the cord 
CORPORA OLiVARiA. — are two anterior pyramids. Ex- 
ternal to these are the corpora olivaria ; and external 
CORPORA RESTiFORMi. — to them are the corpora resti- 
formi which are continuous with the posterior columns 
FOURTH VENTRICLE.— of the cord. The fourth 
ventricle is in the medulla. The medulla plays the 
FUNCTION OF MEDULLA.— part of a conductor 
to and from the brain, presiding also over respiration, 
and is the seat of life. 

THE SPINAL CORD.— rhe spinal cord is com- 
posed of gray matter on the inside, and white matter 
on the outside. It has three distinct covering mem- 



THE NER VO US S YSTEM. 8 3 

branes called by the same names as those covering the 
brain, which they resemble in appearance. The dura 
mater of the cord, however, is separated from the 
POSITION. — bones of the vertebral column. The cord 
lies in a canal formed by a series of vertebra piled one 
LENGTH. — upon another, its length being seventeen 
WEIGHT. — inches, and its weight about an ounce and 
a half. Between the two layers of the arachnoid 
membrane is the cavity of the arachnoid, and beneath 
them is the sub-arachnoidean space. The cord is aided 
LIGAMENTUM DENTICULATUM.— in maintain- 
ing its position by the ligamentum denticulatam. It 
is marked by an anterior and posterior median fissure, 
by anterior and posterior lateral grooves and by trans- 
verse fissures. It has a central canal extending its en- 
tire length and connected with the fourth ventricle. 
Given off from the spinal cord are thirty-one pairs of 
nerves arising from the lateral grooves by anterior and 
posterior roots. The anterior roots are motor; and 
the posterior, sensory. The latter differ from 
the former in having a little body called a 
ganglion situated upon them a short distance from 
their origin. The gray matter is probably inexcitable 
GENERAL PROPERTIES OF THE CORD.— and 



84 THE NERVOUS SYSTEM. 

insensible under direct stimulation. The anterior 
lateral columns are insensible but excitable both on 
their surface and in their substance. The surface of 
the posterior columns is very sensitive, but their deep 
portion is probably insensible. The white substance 
THE CORD AS A CONDUCTOR.— aided by the 
gray of the anterior columns transmits voluntary motor 
stimulus from the brain. The posterior columns 
transmit sensory impressions to the brain, and that 
too, exclusively by the gray matter. The motor and 
sensory fibres decussate within the cord. The cord 
THE CORD AS A CENTRE.—acts as a nervous 
centre generating the stimulus of reflex movements. 
REFLEX MOTION.—Reflex motion is any genera- 
tion of motor nerve force occurring as the result of an 
impression received by a nervous centre. 

THE CRANIAL NERVES.—The cranial nerves 
are divided into twelve pairs by Sommering, and into 
nine pairs by Willis, as follows : — 

Willis. Name. Sommering. 

I St. Olfactory. ist. 

2nd. Optic. 2nd. 

3rd. Motor oculi communis. 3rd. 

4th. Patheticus. 4th. 



THE NERVOUS SYSTEM, 85 

Willis. Name. Sommering. 

5 th. Trifacial. 5 th. 

6th. Motor oculi externus. 6th. 

, ( Facial 7th. 

7^^- lAuditory. 8th. 

r Glosso-pharyngeal. 9lh. 

8th. -l Pneumogastric. loth. 

{Spinal accessory. nth. 

9th. Subungual. 12th. 

THE OLFACTORY NERVE. —The olfactory 
nerve is a special nerve of smell. The optic is a 
THE OPTIC NERVE.— special nerve of sight. 

THE MOTOR OCULI COMMUNIS.— The mo- 
tor oculi communis arises from the optic thalamus, and 
passing out of the brain case through the sphenoidal 
fissure, is distributed to the superior rectus muscle, to 
the internal rectus, to the inferior rectus, to the in- 
ferior oblique, and to the lenticular ganglion of the 
sympathetic. This last distribution is supposed to 
give motor stimulus to the iris. 

THE PATHETICUS.— The patheticus or troch- 
learis is a motor nerve arising from the valve of 
Vieussens, and passing into the orbit through the 
sphenoidal fissure. It is distributed to the superior 
oblique muscle. 



% THE NER VO I ^S S YS TEM. 

THE TRIFACIAL.— The trifacial or trigeminal 
nerve arises in a similar manner to the spinal nerves, — 
by an anterior, motor : and a posterior, sensory root 
with a ganglion upon it. It is the great sensitive nerve 
of the face. The roots arise from the fourth ventricle, 
— the posterior one being the largest. The ganglion 
is called the ganglion of Gasser, or Casser, or semi- 
lunar ganglion, and is situated on the petrous portion 
of the temporal bone. At this ganglion the nerve 
receives branches from the carotid plexus of the sym- 
pathetic. The posterior root enters the concave side 
of the ganglion and coming from its convex side are 
three branches; — the ophthalmic, the superior maxil- 
lary and the inferior maxillary. 

OPHTHALMIC BRANCH.— The ophthalmic 
branch is the smallest of the three divisions, and just 
before it enters the orbit by the sphenoidal fissure, it 
divides into three branches ; — the lachrymal, frontal, 
LACHRYMAL BRANCH.— and nasal. The lachry- 
mal, the smallest of the three, sends a branch to the 
orbital of the superior maxillary ; then passes through 
the lachrymal gland, giving filaments to it, and is 
finally distributed to the conjunctiva and upper eyelid. 
FRONTAL BRANCH.— The frontal branch, the 



THE NERVOUS SYSTEM, 8/ 

largest of the three, divides into the supra-trochlear and 
the supra-orbital nerves. The supra-trochlear passes 
THE SUPRA-TROCHLEAR BRANCH._out of 
the orbit between the supra-orbital foramen and the 
pulley of the superior oblique muscle. It sends a fila- 
ment to the nasal branch and becomes lost in the 
integument of the forehead. The supra- orbital passes 
THE SUPRA-ORBTFAL BRANCH.— through the 
supra-orbital foramen, dividing into muscular, cuta- 
neous, and pericranial branches. It is distributed to 
the eyelids, forehead, mucous membrane of frontal 
sinuses, and to the scalp. The nasal branch before 
THE NASAL BRANCH.— entering the orbit gives 
off a filament to the ophthalmic, ciliary, or lenticular 
ganglion, from which come the short ciliary nerves 
distributed to the ciliary muscle and iris. The nasal 
CILIARY NERVES.— then gives off the long ciliary 
nerves, which are distributed with the short and in the 
same manner. Just before it enters the cranium it 
THE INFRA -TROCHLEAR NERVE.— gives off 
the infra -trochlear branch, which is joined by a fila- 
ment from the supra-trochlear nerve. They pass to 
the nose, eyelid, conjunctiva, orbicularis palpebrarum, 
and lachrymal sac. The original nasal nerve then 



88 THE NERVOUS SYSTEM. 

enters the cavity of the cranium by the anterior eth- 
moidal foramen^ and traverses a groove on the cribri- 
form plate of the ethmoid bone, passing down through 
a sUt by the side of the crysta galli into the nose, 
where it divides into the external and internal nasal. 
INTERNAL NASAL NERVE.—The latter supplies 
the mucous membrane of the nose, while the former 
EXTERNAL NASAL NERVE.— slips out between 
the cartilages and is distributed to the integument of 
the ala and tip of the nose. Both of these branches 
join with the nasal branch of the superior maxillary. 

SUPERIOR MAXILLARY NERVE.—The super- 
ior maxillary branch of the fifth, gets out of the cranial 
cavity by the foramen rotundum, traverses the spheno- 
maxillary fossa in which it gives off the orbital branch, 
that enters the orbit by the spheno-maxillary fissure. It 
then divides into two branches, the temporal and the 
malar. The temporal branch receives a filament from 
the lachrymal, and then passes through a foramen in 
the temporal bone, entering the temporal fossa, to be 
THE TEMPORAL NERVE.— distributed to the in- 
tegument of the temple and side of the forehead. It 
communicates with the auriculo-temporal of the inferior 
maxillary nerve, and with the facial. The malar 



THE XERl^OrS SYSTEiM, 



89 



THE MALAR NERVE— branch comes upon the 
face through a foramen m the malar bone and joins 
with the facial and palpebral branch of this second 
division. In the spheno -maxillary fossa are also given 
SPHENO-PALATINE NERVES. —off two branches 
known as the spheno-palatine, which pass to the sphe- 
SPHENO-PALATINE GANGLION.— no-palatine or 
Meckel's ganglion. This ganglion is situated close to 
the spheno-palatine foramen, and is triangular in 
shape. From it are given off ascending branches 
ASCENDING BRANCHES.— which enter the orbit 
by the spheno-maxillary fissure, and supply the perios- 
teum ; and descending branches, palatine, which are 
distributed to the roof of the mouth, being three in num- 
ber ; — anterior, middle, and posterior palatine. The 
ANTERIOR PALATINE NERVE. —anterior pala- 
tine descends through the posterior palatine canal, and 
emerges at the hard palate at the posterior palatine for- 
amen, supplying the gums and mucous membrane of 
NASAL BRANCHES.— the hard palate. The anter- 
ior palatine gives off nasal branches. The middle pal- 
MIDDLE PALATINE NERVE.— atine descends in 
the same canal with the anterior, and is distributed to 
the uvula and tonsil. The posterior palatine passes 



90 THE NERVOUS SYSTEM. 

POSTERIOR PALATINE NERVE.—through the 
posterior palatine canal, emerging by a separate open- 
ing from the other palatine branches, to supply the 
soft palate. From the posterior portion of Meckel's 
A^IDIAN NERVE. — ganglion comes the vidian nerve, 
which is distributed to the lining membrane of the 
PHARYNGEAL NERVE. —roof of the nose; and a 
pharyngeal branch, distributed to the pharynx. The 
NASAL AND NASO-PALATINE NERVES.— nasal 
and naso-palatine branches are given off from the gan- 
glion, and go to the lining of the ethmoid cells, and 
to the mucous membrane of the mouth. The posterior 
POSTERIOR DENTAL NERVES.— dental branches 
arise from the superior maxillary, just before it enters 
the infra-orbital canal, and are two in number,— the 
anterior and the posterior. The anterior is distributed 
to the gums and buccinator muscle ; while the poste- 
rior branch enters the substance of the superior max- 
illa, to join the anterior dental, supplying the lining 
membrane of the antrum, and the pulps and gums of 
the molar and bicuspid teeth. The superior maxillary 
ANTERIOR DENTAL NERVE.— nerve then enters 
the infra-orbital canal, and gives off the anterior den- 
tal branch which unites with the posterior branch of 



THE NER VO US S VSTEM. 9 1 

the posterior dental, and is distributed to the incisor, 
canine, and first bicuspid teeth. Passing on, the 
superior maxillary nerve emerges upon the face 
through the infra-orbital foramen, and divides into the 
palpebral, labial, and nasal branches. The palpebral 
PALPEBRAL NERVE.—branches are distributed to 
the orbicularis palpebrarum, and to the integument 
and conjunctiva of the lower eyelid, joining with the 
facial nerve, and malar branch of the orbital. The 
NASAL NERVE. — nasal branches supply the muscles 
and integument of the side of the nose, and join with 
the nasal branch of the ophthalmic. The labial 
LABL\L NERVE, — branches are distributed to the 
muscles and integument of the upper lip, and form 
the ganglion of Cloquet. 

INFERIOR MAXILLARY NERVE. —The in- 
ferior maxillary nerve is the largest of the three divi- 
sions of the fifth, and includes in its composition the 
motor root of the fifth pair which joins with it just 
after it leaves the brain case by the foramen ovale. 
Outside the cranium it divides into two trunks, — an 
anterior and a posterior. The anterior or smaller 
ANTERIOR DIVISION— division receives almost 
all of the motor root, and divides into five branches ; 



92 THE NERVOUS SYSTEM, 

— the masseteric, deep temporal, buccal, external and 
internal pterygoid ; which are distributed to muscles 
POSTERIOR DIVISION.— of the same names. The 
posterior and larger division of the inferior maxillary 
divides into three branches, — the auriculo-temporal, 
gustatory, and inferior dental. The auriculo-temporal 
AURICULO-TEMPORAL NERVE.— divides into 
the anterior and the posterior temporal. The anterior 
ANTERIOR TEMPORAL NERVE.— temporal 
supplies the integument of the temporal region. The 
POSTERIOR TEMPORAL N E R V E.— posterior 
temporal supplies the integument of the ear, and joins 
with the temporal branch of the superior maxillary. 
GUSTATORY NERVE.— The gustatory or lingual 
nerve is distributed to the mucous membrane of the 
tongue as far as the point, giving branches to the sub- 
maxillary ganglion, and receiving an important branch 
from the facial, — the chorda tympani, which is sup- 
posed to give to the gustatory its sense of taste. The 
INFERIOR DENTAL NERVE.— inferior dental, the 
largest division of the inferior maxillary, gives off just 
MYLO-HYOID NERVE.— before it enters the dental 
foramen, the mylo-hyoid nerve to supply the mylo- 
hyoid and digastric muscles. It then enters the dental 



THE XER VOL'S SYSTEM. 



93 



foramen, traverses the dental canal in the inferior 
INCISOR BRANCH.— maxillary bone as far as the 
mental foramen, where it divides into the incisor, and 
MENTAL BR AN'C H . —the mental branch . The lat- 
ter emerges from the bone at the mental foramen, 
dividing into external and internal branches, which 
are distributed to the structure of the lip. In the canal 
branches are given off which supply the teeth of the 
THE OTIC GANGLION.— lower jaw. The otic or 
Arnold's ganglion is an oval-shaped body, situated 
below the foramen ovale, on the inner surface of the 
inferior maxillary nerve. The large root of the tri- 
FUNCTIONS OF THE TRIFACIAL NERVE.— 
facial is exclusively a sensory nerve, therefore its 
branches, — the superior maxillary and ophthalmic, 
and the nerves arising from them are sensory only. 
The inferior maxillary including the motor root is 
therefore both motor and sensory. Thus the hfth 
pair is a mixed nerve in its functions ; — being motor, 
sensory, and a nerve of special sense. 

MOTOR OCULI EXTERNUS NERVE.— The 
motor oculi externus arises from the floor of the fourth 
ventricle, enters the orbit by the sphenoidal fissure, 



94 THE NER VO US S YSTEM, 

FUNCTION. — and' is distributed to the external rectus 
muscle to give it motor stimulus. 

AUDITORY NERVE._The auditory, or portia 
mollis of the seventh pair, is a special nerve of hear- 
FACIAL NERVE.— ing. The portia dura, the other 
division of this pair, arises from the floor of the fourth 
ventricle, passes in connection with the auditory and 
intermediary nerve of Wrisberg into the internal audi- 
tory meatus. At the bottom of the meatus, the facial 
nerve and the nerve of Wrisberg enter the aqueductus 
Fallopii, and pass through the petrous portion of the 
temporal bone, where the intermediary nerve unites 
with the main root forming the common trunk of the 
facial, which emerges by the stylo-mastoid foramen. 
LARGE PETROSAL NERVE.— In the aqueductus 
Fallopii the facial gives off the large petrosal branch, 
SMALL PETROSAL NERVE.— which goes to Meck- 
el's ganglion ; the small petrosal, which goes to the 
TYMPANIC NERVE.—otic gangUon; the tympanic 
branch to the stapedius muscle ; the chorda tympani 
CHORDA TYMPANI NERVE.— to the lingual 
branch of the inferior maxillary ; and a branch to the 
pneumogastric. After passing out of the stylo-mastoid 
POSTERIOR AURICULAR NERVE foramen, 



THE NERVOUS SYSTEM, 95 

it sends a branch to the glosso-pharyngeal ; one to the 
stylo-hyoid muscle ; the posterior auricular nerve to 
the occipito-frontalis muscle and those around the ear; 
DIGASTRIC NERVE.— and the digastric branch to 
the digastric muscle. The trunk then passes through 
the parotid gland and divides into the temporo-facial, 
which is distributed to the superficial muscles of the 
upper part of the face ; and into the cervico -facial 
which passes to supply the muscles in the lower part 
of the face. The facial nerve is the motor nerve of 
FUNCTIONS OF THE FACIAL NERVE.—the 
superficial muscles of the face, and is the only nerve 
that animates the buccinator muscle. 

GLOSSO-PHARYNGEAL NERVE.— The glosso- 
pharyngeal is the first division of the eighth pair of 
nerves, and is a nerve of taste. 

PNEUMOGASTRIC NERVE.— The pneumogas- 
tric, the second division of this pair, arises from the 
floor of the fourth ventricle, enters in the jugular for- 
amen into the jugular ganglion, and then makes its exit 
from the cranial cavity by the jugular foramen, or 
posterior foramen lacerum. It receives filaments of 
communication from the spinal accessory, facial, and 
sublingual nerves ; and from the sympathetic nervous 



96 THE NER J V as S i 'S TEJL 

system. It gives off the auricular branch to the integ- 
AURICULAR BRANCH.— ument around the exter- 
nal auditory meatus ; the pharyngeal nerves which go 
PHARYNGEAL NERVES.— to the muscles and mu- 
cous membrane of the pharynx ; the superior laryngeal 
SUPERIOR LARYNGEAL NERVES.— which give 
sensibility to the upper part of the larynx, animating 
the crico- thyroid muscle and the inferior constrictor 
of the pharynx ; the inferior laryngeal which animate 
INFERIOR LARYNGEAL NERVES.— the intrinsic 
muscles of the larynx, except the crico-thyroid ; the 
CARDIAC NERVES. — cardiac branches w^hich go 
PULMONARY NERVES.— to the cardiac plexus; 
the pulmonary branches distributed to mucous mem- 
CESOPHAGEAL NERVES.— brane; the oesophageal 
branches distributed to the muscular and mucous tissue 
of the lower part of the oesophagus ; and the abdomi- 
ABDOMINAL BRANCHES.— nal branches which 
pass to the stomach and organs in the abdominal cav- 
FUNCTIONS OF PNEUMOGASTRIC NERVE.— 
ity. The pneumogastric nerve being in its origin 
strictly sensory, gives sensibility around the ear, to the 
pharynx, and to the upper part of the larynx ; regulates 
the protection of the air passages ; has to do with the 



THE NER J O US S YSTEM, 97 

reflex action of deglutition, the vocal and respiratory 
movements, the action of the heart, the movements of 
the oesophagus ; and influences the abdominal organs. 

SPINAL ACCESSORY NERVE.— The spinal ac- 
cessory, the third division of the eighth nerve, arises 
in part from the lower portion of the medulla oblong- 
ata, and in part from the cervical portion of the spinal 
cord. It enters the cranial cavity by the foramen 
magnum, and emerges by the jugular foramen. It 
ANASTOMOTIC BRANCH.— divides into the inter- 
nal or anastomotic branch which passes to the pneu- 
mogastric nerve, and through its recurrent laryngeal 
to the larynx ; and into an external or muscular branch 
MUSCULAR BRANCH.—which is distributed to the 
sterno-cleido-mastoid and trapezius muscles. The true 
FUNCTIONS OF THE SPINAL ACCESSORY.— 
origin of the spinal accessory is motor in its nature, 
and besides supplying the above-named muscles, it 
gives motor influence to the distribution of the pneu- 
mogastric. 

SUBLINGUAL NERVE.— The sublingual or hypo- 
glossal nerve arises from the floor of the fourth ventri- 
cle, and passes out of the cranial cavity through the 
anterior, condyloid foramen. It then gives off the 



98 THE NERVOUS SYSTEM. 

DESCENDENS N( )NI— descendens noni to the sterno- 
hyoid, sterno-thyroid, and omo-hyoid muscles; and 
THYRO-HYOID NERVE— the thyro-hyoid branch 
to the thyro-hyoid muscles. Its other branches go to 
the stylo-glossus, hyo-glossus, genio-hyoid, and genio- 
hyo-glossus and intrinsic muscles of the tongue. The 
FUNCTIONS OF THE SUBLINGUAL.— sublin- 
gual is a motor nerve, and its functions are connected 
with the tongue in articulation and digestion. 

SYMPATHETIC NERVOUS SYSTEM._The 
sympathetic nervous system is composed of from 
twenty- eight to thirty ganglia, on either side of the 
spinal column, terminating below in the ganglion of 
FUNCTIONS. — impar. It presides over the functions 
of animal life, and has an important influence upon 
nutrition, calorification, and secretion. 

VASO-MOTOR NERVES.— The vaso-motor 
nerves are distributed from the cerebro-spinal system 
to the bloodvessels to regulate their calibre. 




THE SPECIAL SENSES. 



VISION. — The optic nerves arise from the tubercula 
quadrigemina, and pass to the optic commissure or 
chiasm which rests upon the ohvary process of the 
OPTIC COMMISSURE.— sphenoid bone, and is the 
point of union between the nerves of the two sides. 
The fibres of each side divide here, a part going to the 
eye of their own side, and a part to the eye of the 
other side. The optic nerves are not endowed with 
general sensibiUty, and only convey the impressions 
of sight. Any irritation of them produces the impres- 
sion of light. 

THE EYEBALL. — The eyeball is spheroidal and 

placed in a cushion of fat in the orbit, and has three 

SCHLEROTIC COAT.— coats. The outer one is 

called the schlerotic on account of its hardness, and is 

dense, opaque and fibrous. It covers the posterior 

five-sixths of the globe being continuous with the cor- 

99 



100 THE SPECIAL SENSES. 

CORNEA. — nea, — a transparent dense resisting mem- 
brane, which covers the anterior one-sixth of the eye- 
ball. The cornea is made up of complete and dis- 
tinct layers, which allow the passage of light. It is 
mserted into the schlerotic coat in the same manner 
that the watch-crystal is into its bevel. The second 
CHOROID COAT.— coat, the choroid, is of a dark 
color and highly vascular. It is lined by a layer of 
PIGMENTUM NIGRUM.— black pigment, called 
the pigmentum nigrum, which prevents too great re- 
flection of the rays of light in the eye. The anterior 
CILIARY PROCESSES.— portion of the choroid coat 
is thrown into about sixty or eighty folds, called the 
ciliary processes, and arranged around the margin of 
CILIARY MUSCLE.— the crystalline lens. The cil- 
iary muscle is an organ of great importance, as it aids 
in accommodating the eye to different distances. It 
surrounds the anterior margin of the choroid coat, 
and acts to tighten this coat over the vitreous humor. 
IRIS. — The iris is made up of circular and transverse 
muscular fibres, and corresponds to the diaphragm of 
optical instruments. It is circular and is situated in 
front of the crystalline lens, with a perforation in its 
PUPIL, — centre, — the pupil. The color of the iris, 



THE SPECIAL SENSES. lo I 

due to pigmentary cells, is different in different indi- 
viduals. The circular fibres contract, and the trans- 
verse dilate the pupil. Across the pupil in foetal life 
PUPILLARY MEMBRANE._is the pupillary mem- 
RETINA.— brane. The third coat of the eye, the 
retina, is essentially an expansion of the optic nerve ; 
and is an important structure as it is endowed with the 
sense of sight. It consists of a delicate transparent 
membrane. The optic nerve penetrates the retina a 
little internal and below the antero-posterior axis. It 
BLIND SPOT. — is perforated in its centre for the 
ARTERIA CENTRALIS RETINA. —passage of the 
central artery of the retina, thus making the blind 
MACULA LUTEA.— spot of the eye. External to 
the point of penetration of the nerve is the yellow 
spot of Sommering, or macula lutea, — the most sensi- 
tive point of the retina. The retina is made up of 
RODS AND CONES —layers. The layer of rods 
and cones is situated next to the choroid coat, and 
above it are four granular layers, covered by one of 
nerve-cells and nerve fibres. In apposition with the 
hyaloid membrane of the vitreous humor, is the mem- 
brana limitans. The rods are supposed to take cog- 
nizance of the color of light; and the cones, the 
quantity or intensity. 



I02 THE SPECIAL SENSES. 

CRYSTALLINE LENS._In the eye is a double 
convex, transparent, and elastic lens, having a func- 
tion in the refraction of the rays of light. It is situ- 
ated behind the pupil in the hyaloid fossa of the 
vitreous humor. It is more convex on its posterior, 
than on its anterior surface ; and is composed of lay- 
CAPSULE OF LENS._ers of fibres of different 
densities, covered by a capsule which is an exceedingly 
thin, elastic membrane. The hyaloid membrane of 
the vitreous humor is attached to the capsule of the 
lens forming its suspensory ligament. The folds of 
ZONE OF ZINN.. — the ligament are received between 
the folds of the ciliary processes, and are known as 
AQUEOUS HUMOR.— the zone of Zinn. The 
space bounded in front by the cornea, and posteriorly 
by the crystalline lens, is filled with a clear liquid 
known as the aqueous humor. This substance is 
faintly alkaline, and has a specific gravity of 1005. 
ANTERIOR CHAMBER.— The portion of this space 
between the anterior face of the iris and the cornea, is 
called the anterior chamber; and that between the 
POSTERIOR CHAMBER.—posterior face of the iris 
and the capsule of the lens, is known as the posterior 
VITREOUS HUMOR. —chamber of the eye. The 



THE SPECIAL SENSES. 103 

vitreous humor is a clear, glassy substance, enveloped 
by a hyaloid membrane, situated in the posterior two- 
thirds of the globe. It is alkaline in reaction and has 
a specific gravity of 1005. 

LIGHT. — The theory of undulation as regards 
light is accepted to-day and the emission theory of 
Newton rejected. According to the former all space 
is filled with an ether, and light is propagated by 
VELOCITY. — a vibration of it. The velocity of light 
COLOR. — is 192,000 miles in a second and the color 
is determined solely by its wave length. When white 
COMPOSITION. — light is decomposed it gives seven 
colors; — violet, indigo, blue, green, yellow, orange, 
REFLECTION. — and red. A ray of light falling on a 
smooth3 polished surface, is reflected in the opposite 
direction at the same angle as that from which it comes. 
The ray which thus falls is called the incident ray, and 
the other the reflected ray. The angle produced by 
the former with the perpendicular, is termed the angle 
of incidence ; and that by the perpendicular and the 
latter, the angle of reflection. The angle of reflection 
REFRACTION. — is always equal to the angle of incidence. 
Light which passes from a rarer to a denser medium, or 
the reverse, is always bent or refracted from its course. 



I04 



THE SPECIAL SENSES. 



SPHERICAL ABERRATION.—Spherical aberration 
is the absence of sphericity, and is caused by the rays 
of Ught not forming a single focus. Chromatic aber- 
CHROMATIC ABERRATION.—ration is the de- 
composition of the ray of Hght into the colors of the 
spectrum, and is the result of the unequal action of 
the refracting medium. In optical instruments chro- 
matic aberration is corrected by a combination of 
lenses made of crown and flint glass. 

ASTIGMATISM. — Astigmatism is that disease of 
the eyes, in which one sees the lines of an object run- 
ning in one direction, without seeing those running in 
MOVEMENTS OF THE IRIS.— another. The 
movements of the iris are reflex, acting under the 
stimulus of light. The eye is accommodated to difl'er- 
ACCOMMODATION OF THE EYE TO DIS- 
TANCE. — ent distances by changing the convexity of 
the lens. The range of vision varies between five in- 
PRESBYOPIA. — ches and infinity. Presbyopia, or 
long sightedness, is corrected by the use of convex 
MYOPIA. — lenses. Myopia, or short sightedness, by 
concave ones. 

ERECT VISION. — The retina does not perceive 
as a whole organ, but each individual bacillus in it 



THE SPECIAL SENSES, 105 

perceives its share of the picture formed upon the 
general surface ; and as the bacilli stand radially upon 
the inner aspect of the eyeball, they are so directed 
that each will see its part of the object in the proper 
DURATION OF IMPRESSIONS. —position. Im- 
pressions made upon the retina remain the sixth of a 
MUSCLES OF THE EYEBALL.— second. The 
muscles which move the globe of the eye are; — the 
external and internal recti, superior and inferior recti, 
and two oblique muscles. The eye is protected by 
eyelids. The outer and inner angles formed by these 
CANTHUS. — lids, are known as the outer and inner 
canthus. The principal muscles which open and 
close the eyelids are the orbicularis palpebrarum, 
and the levator palpebrse superioris. The inner 
CONJUNCTIVA. —surface of the hds is Hned by 
a mucous membrane, which is reflected over the 
eyeball, and is known as the conjunctiva. The eye- 
LACHRYMAL GLAND.— ball is constantly bathed 
by a thin, watery fluid, which is secreted by the lach- 
rymal gland. The lachrymal gland is ovoid, flattened, 
and of the racemose variety. It is situated in the 
upper and outer part of the orbit. The excess of the 
PUNCTA LACHRYMALIA.— lachrymal secretion 



Io6 THE SPECIAL SENSES. 

is carried into the nose by the pimcta lachrymalia, two 
minute openings situated one on each lid, near the 
inner canthus, and opening into the lachrymal canals. 
LACHRYMAL CANALS.—These canals form the 
NASAL DUCT. — nasal duct, a tube half an inch in 
length, opening into the nose.^ On the borders of the 
lids are short, stiff hairs, curved away from the eye- 
ball, which serve to shade the eye and protect the 
MEIBOMIAN GLANDS.— globe from dust. Along 
the edges of the lids are the meibomian glands, which 
secrete an oily substance, that prevents the overflow 
of the tears. 

AUDITION. — The auditory nerve constitutes the 
portia mollis of the seventh, and arising from the floor 
AUDITORY NERVE.—of the fourth ventricle en- 
ters the internal auditory meatus, where it divides into 
an anterior and a posterior branch. The anterior 
branch goes to the cochlea, and the posterior to the 
vestibule and semicircular canals. The auditory is a 
nerve of special sense, not endowed with general sen- 
sibility, and only capable of conveying impressions of 
sound. 

EAR. — The ear is divided into the external, middle, 
and internal ears. 



TkE SPECIAL SENSED, 1 67 

EXTERNAL EAR— The external is made up of the 
PINNiV. — pinna or auricle, which is the portion pro- 
HELIX. — ejecting from the head. Externally in it is 
the helix, which is the outer ridge of the pinna. 
FOSSA OF HELIX.— Within this is a groove called 
the fossa of the helix, bounded anteriorly by a shorter 
ANTI-HELIX.—ridge called the anti-heHx. Between 
FOSSA OF ANTI-HELIX. —the superior portion of 
the anti-helix and the anterior portion of the helix is 
CONCHA. — the fossa of the anti-helix. The fossa 
immediately around the opening of the meatus is 
TRAGUS. — called the concha. A lobe projects pos- 
ANTI-TRAGUS— teriorly called the tragus. A pro- 
jection at the lower part of the anti-helix is called the 
LOBULE. — anti- tragus. The dependent portion of 
the ear is called the lobule. The external auditory 
EXTERNAL AUDITORY MEATUS.— meatus is 
an opening about an inch and a quarter in length and 
extends from the concha to the middle ear. 

MIDDLE EAR. —The middle ear is a narrow 
cavity of irregular shape, situated between the exter- 
nal and the internal ear, in the substance of the 
MEMBRANA TYMPANL— temporal bone. Its outer 
wall is formed by the membrana tympani, a concave 



log THE SPECIAL SENSES. 

membrane, which incHnes at an angle of forty- five de- 
grees. The floor and roof are bone. The inner wall 
towards the internal ear presents elevations and fora- 
FENESTRA OVALIS— mina. The fenestra ovalis, 
an ovoid opening near its upper part, leads to the 
FENESTRA ROTUNDA.—cavity of the vestibule ; 
while below is a smaller opening, — the fenestra ro- 
tunda, leading to the cochlea. This cavity also pre- 
EUSTACHIAN TUBE.—sents an opening, which 
leads by the eustachian tube to the upper part of the 
pharynx. The middle ear is lined by mucous mem- 
brane, which is continuous with that of the mastoid 
cells opening into the cavity. It contains the bones 
of the ear, — the incus, malleus, and stapes. The mal- 
MALLEUS. — leus is so called from its being shaped 
like a hammer, and has its handle closely attached to 
INCUS. — the membrana tympani. It articulates with 
the incus, so-called from its resemblance to an anvil, 
which in turn is connected with the posterior wall of 
STAPES. — the cavity near the mastoid cells, and is 
articulated by its long process with the stapes, a stir- 
rup shaped bone having its oval base applied to the 
fenestra ovahs. These bones are moved by muscles. 
INTERNAL EAR.— The internal ear is contained 



THE SPECIAL SENSES. 



109 



in the petrous portion of the temporal bone, and is 
BONY LABYRINTH.— composed of an irregular 
cavity, called the vestibule, the semi-circular canals 
and the cochlea. It is named the bony labyrinth. 
VESTIBULE. — The vestibule is the central chamber 
SEMI-CIRCULAR CANALS.— of the labyrinth, and 
in its posterior wall are five openings leading to the 
semi-circular canals, and a larger one to the cochlea. 
The semi-circular canals are three in number. The 
COCHLEA. — cochlea is a spiral canal about an inch 
and a half long, tapering to an apex, and making in 
FENESTRA ROTUNDA— its course two and a half 
turns. The fenestra rotunda, closed by a membrane 
SECONDARY MEMBRANA TYMPANL— called 
the secondary membrana tympani, is an opening by 
which the cochlea communicates with the middle ear. 
MEMBRANOUS LABYRINTH.— The bony laby- 
rinth is lined by periosteum, and contains a membra- 
LTTRICLE. — nous labyrinth. The membranous ves- 
tibule is divided into the utricle and saccule. The 
SACCULE. — saccule opens into the membranous 
canal of the cochlea. At the point where the audi- 
OTOLITHS. — tory nerve enters the saccule and utri- 
cle, are little masses of crystals of carbonate of lime 



no THE SPECIAL SENSES, 

called otoliths. Otoliths also exist in the enlarged por- 
AMPULLxVE. — tions of the membranous semi-circu- 
lar canals, — the ampullae. The membranous laby- 
PERILYMPH.—rinth floats in a liquid called the 
ENDOLYMPH. — perilymph, and within it is another 
liquid called the endolymph. The organ of Corti is 
ORGAN OF CORTI. — supposed to receive sonorous 
vibrations, and to communicate them to the terminal 
filaments of the auditory nerve. It is situated in the 
quadrilateral canal throughout its spiral course. The 
FUNCTION OF SEMI-CIRCULAR CANALS.— 
semi-circular canals are supposed to appreciate quality 
FUNCTION OF COCHLEA._of sound; and the 
cochlea, the wave lenth. The internal ear is the essen- 
tial portion of the organ of hearing. 

TOUCH. — The sense of touch is the appreciation of 
contact, and the result of the anatomical arrangement 
of the termination of the sensory nerves. This sense 
is capable of education, and of extraordinary develop- 
ment. It is most acute in those situations in which the 
tactile corpuscles are the most abundant. The appre- 
ciation of temperature is the result of the nerves of 
general sensibility. 

SMELL.— ^The two irregular shaped cavities in the 



THE SPECIAL SENSES. 1 1 1 

middle of the face, opening in front by the anterior 
NASAL FOSSAE. — nares, and into the pharynx by 
the posterior nares, are called the nasal fossae. The 
S C H NE IDERI A N MEMBRANE— mucous mem- 
brane lining these cavities is called the Schneiderian 
membrane, and in its upper half is the essential organ 
OLFACTORY NERVES.— of smell. The olfactory 
nerve arises from the inferior and internal portion of 
the anterior lobe of the cerebrum, and passes forward 
to the ethmoid bone, expanding beside the crysta galli 
into an oblong ganglion, called the olfactory bulb. 
From this bulb fifteen to eighteen filaments descend 
through the cribriform plate of the ethmoid into the 
nasal fossae, and are distributed to the mucous mem- 
FUNCTIONS. — ^brane. The olfactory ners^es being 
special nerves of smell are insensible to ordinary im- 
pressions. The mechanism of olfaction consists in the 
contact of material emanations of odorous substances 
with the nerves of smell. The sense of smell is closely 
related to the sense of taste, and we lose the delicacy 
of the sense of taste when the sense of smell is abolished. 
GUSTATION.— The sense of taste enables us to 
appreciate the savor of substances introduced into the 
CHORDA TYMPANI NERVE.— mouth. Two 



I 1 2 THE SPECIAL SENSES. 

nerves, the chorda tympani and the glosso -pharyngeal, 
preside over the sense of taste. The chorda-tympani 
is a branch of the facial, and enters the tongue through 
the lingual branch of the fifth, to supply the anterior 
GLOSSO-PHARYNGEAL.— two-thirds. The glosso- 
pharyngeal, the first division of the eighth pair, arises 
from the medulla oblongata, and gets out of the brain 
case through the foramen lacerum. It sends branches 
to the digastric and stylo-hyoid muscles, and is finally 
distributed to the tonsils, soft palate, and posterior 
portion of the tongue. It acts as a nerve of special 
and general sensibility. The organ of taste is confined 
TONGUE. — to the dorsal portion of the tongue. The 
tongue is a symmetrical muscular organ developed on 
either side of a median fibrous layer which arises from 
the hyoid bone. It is situated in the oral cavity, and 
is divided into a cortex and a medullated portion. It 
CIRCUMVALLATE PAPILLAE._has at its base 
circumvallate papillae arranged in the form of a V. 
FUNGIFORM PAPILLAE.— These are simply en- 
larged fungiform papillae, which are short and thick, 
with rounded extremities. The fungiform papillae are 
placed all over the tongue, being most numerous how- 
ever at the tip and sides. The fungiform and circum- 



THE SPECIAL SENSES. 113 

vallate papillae alone are the organs of taste. The 
FILLIFORM PAPILLAE.—filliform papillae are 
scattered over the surface between the fungiform papil- 
TASTE BUDS. — lae. Taste buds are found on the 
circumvallate and and fungiform papillae, being flask- 
shaped collections of spindle -like cells, having a 
rounded opening called the taste pore. Sapid sub- 
stances find their way into the interior of these struct- 
ures, and thus come in contact with the taste cells, 
which are in connection with the terminal filaments 
of the gustatory nerve. 



GENERATION. 



GENERATION— Generation is the function by 
which the species of a plant or animal is preserved, 
and its existence perpetuated. 

FEMALE ORGANS.— The female organs are di- 
vided into internal and external ones. The external 
organs are the vulva and adjacent parts, and the vagi- 
na. The internal organs are the uterus. Fallopian 
VAGINA. — tubes, and ovaries. The vagina has a 
curved direction, and projecting into its upper part is 
the neck of the uterus. It is four inches long, and its 
inner surface is marked by rugae. The clitoris corres- 
CLITORIS. — ponds to the penis of the male. The 
UTERUS. — uterus is situated between the bladder 
and the rectum, being held in place by ligaments. It 
is pear-shaped, about three inches in length, and 
weighs from one and a half to two and a half ounces. 

It is composed of muscular structure of the involuntary 

114 



GENERA TION, 1 1 5 

character, arranged in several layers, and is lined by 
FALLOPIAN TUBES.— mucous membrane. The 
Fallopian tubes lead from the ovaries to the uterus, 
and are from three to four inches long. Their ex- 
tremities near the ovary are marked by from ten to 
fifteen fimbriae, which have given the name of the 
fimbriated extremities. All of the fringe-like extremi- 
ties are free but one, and this is attached to the ovary. 
OVARIES. — The ovaries are attached to the broad 
ligament of the uterus, and project into its posterior 
surface. They are of a whitish color, ovoid, and flat- 
tened in form, and are each about an inch and a half 
in length, and are composed of a cortical portion and 
a medullary portion. The cortical substance alone 
GRAAFIAN FOLLICLES.— contains the Graafian 
follicles, being composed of connective tissue, in the 
OVUM. — substance of which the ova are imbedded 
enclosed in sacs called the Graafian follicles. These 
ova cells are found iu different stages of development, 
and no additional ones make their appearance after 
birth. They enlarge, approach the surface, and are 
finally ruptured, discharging their contents into the 
fimbriated extremity of the Fallopian tubes. 

VITELLINE MEMBRANE.— The ripe ovum lies 



1 1 6 GENERA TION. 

in the Graafian follicle covered by an external mem- 
VITELLUS. — ^brane, — the vitelline membrane. 
Within the membrane is a granular mass, called the 
vitellus; a large, clear nucleus called the germinal 
vesicle \ and a nucleolus, called the germinal spot. At 
the time of the rupture of the Graafian follicle, the 
fimbriated extremity of the Fallopian tube is applied 
to the ovary for the reception of the ovum, and con- 
veys it into the uterus. 

PUBERTY — Between the ages of thirteen and 
fifteen years the human female arrives at puberty, and 
undergoes a change. Hair grows upon the mons 
veneris ; the mammary glands develop ; the Graafian 
follicles enlarge ; the female becomes capable of im- 
MENSTRUATION.— pregnation ; and a periodical, 
sero-mucous discharge takes place from the genital or- 
gans constituting menstruation, which afterwards re- 
occurs monthly until it ceases at or about the age of 
fifty years. The interval between the flow from end- 
ing to beginning is twenty -eight days; and from be- 
ginning to ending, about five days. During pregnancy 
and lactation it is generally absent. Menstruation is 
identical with ovulation, and the blood comes from 
the lining membrane of the uterus. 



GENERATION. \\J 

MALE ORGANS OF GENERATION.— The 
penis is the organ of copulation, and passing through 
it is the urethra which serves to emit the product of 
TESTICLES. — the testicles. The testicles are two 
symmetrical organs situated during intra-uterine life 
in the abdominal cavity, but finally descending into 
the scrotum, a pouch-like process of the skin. Beneath 
SCROTUM. — the integument of the scrotum is a 
contractile tissue called the dartos. The testicles are 
SPERMATIC CORD.—suspended in the scrotum by 
the spermatic cords, which are composed of the vas 
deferens, blood vessels, and nerves. The coverings 
of each testicle are, — the inter-columnar fascia, the 
cremaster muscle, the infundibuliform fascia, the 
tunica vaginalis, and the proper fibrous coat or tunica 
albuginea, beneath which is the tunica vasculosa. Each 
SEMINIFEROUS TUBES.—testicle is composed of 
about eight hundred and forty tubes known as the 
seminiferous tubules, in which the male elements are 
VAS DEFERENS.— formed. The vas deferens is the 
excretory duct of the testicle. It is nearly two feet in 
its entire length, joining with the seminal vescicle, 
forming the ejaculatory duct, which opens into the 
prostatic portion of the urethra. Attached to the. 



Ilg GENERATION. 

VESICULAE SEMINALES.— base of the bladder 
and situated externally to the vasa deferentia are 
two vesiculae seminales, composed of a coiled saccu- 
lated tube, and serving as receptacles for the seminal 
PROSTATE GLAND.— fluid. The prostate gland 
secretes a fluid which forms a part of the ejaculated 
semen. 

SEMEN. — The seminal fluid is composed of ele- 
ments from the testicle, mixed with the secretions from 
the vasa deferentia ; from the vesiculae seminales ; from 
the glands of the prostate ; and from the glands of the 
urethra. It is slightly mucilaginous, of a grayish white 
color, does not mix with water nor contain albumem, 
SPERMATOZOIDS.— and in reaction is alkaline. In 
the semen are anatomical elements known as spermato- 
zoids, endowed with movements like ciliated epithelium, 
having flattened, conoidal heads and a long, tapering, 
COITUS. — filamentous tail in active motion. Coitus 
is accomplished by the introduction of the penis into 
the vagina of the female. The penis of the male is 
made erect by turgescence of blood, and becomes 
sensitive especially at the glans. The introduction 
of the organ into the vagina, the pressure of its 
constrictor muscle, and friction increase the sensibility 



GENERATiOM. 1 19 

until the venereal orgasm occurs, when the semen 
is discharged. Coitus in the female is accomplished 
by the erection of the clitoris^ turgidity of the vessels 
of the vagina, and increase in the secretions, culmin- 
ating in an orgasm similar to that of the male. 

FECUNDATION— Fecundation is accomplished 
by a union of the ovum of the female with the sperma- 
tozoids in the semen of the male. This molecular 
union between the two elements is followed by the re- 
markable changes of development. The vitellus of the 
SEGMENTATION OF THE VITELLUS. —ovum be- 
comes divided into numerous cells, called blastodermic 
cells. This process is termed segmentation of the vitellus. 
A membrane is soon formed over these cells known as 
the blastodermic membrane, which is afterwards divi- 
ded into layers of cells from which the embryon comes. 
AMNION. — The membrane enclosing the embryon is 
ALLANTOIS. — called the amnion ; that surrounding 
the amnion, the allantois or chorion. The fluid within 
AMMIOTIC FLUID,_the amnion is termed the 
UMBILICAL CORD.— amniotic fluid. The umbilical 
cord is the pedicle which connects the embryon with 
that portion of the chorion which enters into the con- 
PLACENTA.— struction of the placenta. The pla- 



I 20 GENERA TIOM. 

centa is the organ by which the foetus derives its 
nourishment, and is composed of a maternal portion 
from the mucous membrane of the uterus, and a foetal 
portion from the vascular part of the chorion. The 
FOETUS. — embryon is called the foetus at the fourth 
month. During gestation the uterus is enlarged but 
returns to normal size after delivery. The duration of 
pregnancy is two hundred and sixty to three hundred 
days. Parturition is the process by which the foetus is 
expelled. 




SLEEP AND DEATH. 



SLEEP. — One -third of our existence is passed in 
sleep, and in it the functions of the body are greatly 
modified. Sleep is more important in infancy and 
youth, than in adult life and old age. During sleep 
the brain is in a condition of absolute repose. Sleep 
is the result of a diminution of the supply of the blood 
to the brain. 

DREAMS. — Dreams are automatic actions of the 
brain originating from impressions received from ex- 
ternal sounds, while going to sleep or waking, or from 
impressions previously made upon the registering 
ganglia of the brain. 

DEATH. — Any thing which interferes with the 
functional activity of the system in the processes which 
repair its constant waste, will result in the phenom- 
enon called death, after which the organism decays 
and the products of its decomposition are appropriated 
by the vegetable kingdom, 

131 



TABLE OF SPECIFIC GRAVITIES. 



Name. 


Specific Gravity. 


Sweat. 


1004. 


Saliva. 


1005. 


Gastric Juice. 


1005. 


Aqueous humor. 


1005. 


Vitreous humor. 


1005. 


Lymph. 


1007. 


Urine. 


1015 to 1025. 


Chyle. 


1024. 


Bile. 


1018 to 1026. 


Plasma. 


1028. 


Milk. 


1032. 


Gray nervous matter. 


1034. 


Brain. 


1036. 


White nervous matter. 


1040. 


Pancreatic Juice. 


1040. 


Colostrum. 


1046 to 1060. 


Blood. 


1052 to 1057. 


White corpuscles. 


1070. 


Red corpuscles. 


1088 to 1105. 



